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Availability:
In Stock.
Arrives
Wednesday, Aug 26
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Size: California King
Style: 4 Inch
Color: Blue Gel
Features
- Memory Foam
- COOLING GEL INFUSION: This cooling gel memory foam mattress topper is designed to sleep cooler; gel infused directly into the foam draws heat away from your body and regulates mattress topper memory foam temperature all night.
- ULTRA PLUSH, SINK-IN FEEL: This ultra plush 4 inch mattress topper has an extra thick profile with plush memory foam that conforms to every curve, ideal for firm beds or worn mattresses.
- BREATHABLE, VENTILATED DESIGN: Precision-cut ventilation channels run throughout this foam mattress topper, promoting airflow and keeping this mattress foam topper surface fresh, breathable, and comfortable all night.
- CERTIFIED FOR YOUR PEACE OF MIND: This memory foam mattress topper is CertiPUR-US certified tested by independent labs for content, emissions, and mattress foam durability; backed by a 3-year limited warranty.
- EASY SETUP, READY WHEN YOU ARE: This mattress topper and foam bed upgrade ships compressed and rolled; just unbox it, unroll it on your bed frame, and allow 2448 hours to expand.
Description
Ready for a better night’s sleep? You don’t always need a new mattress to get there—sometimes all it takes is the right topper. The Lucid® Cooling Gel Memory Foam Topper is designed to bring new life to your existing bed. Cooling gel infused directly into the foam works to draw heat away from your body and regulate sleep temperature, and precision-cut ventilation channels run throughout the foam to keep airflow moving. Find the profile that’s right for you. Two inches of memory foam adds a soft, responsive layer that gently cushions pressure points and conforms to your body’s natural shape. Three inches of memory foam offers deeper pressure relief, contouring closely to your hips, shoulders, and back so you wake up feeling rested, not stiff. Four inches of deep, responsive memory foam creates a cloud-like feel that’s perfect for firm mattresses, beds that have seen better days, or anyone who just wants to seriously sink in. CertiPUR-US® certification means the foam has been independently tested for content, emissions, and durability. A 3-year manufacturer’s warranty helps you have peace of mind with your purchase. This bed topper ships compressed and rolled in a box. It’s easy to move, and easy to set up. Unbox it, unroll it, and give it 24–48 hours to fully expand. Better sleep doesn’t need to be complicated. For best results, pair with a Lucid® waterproof mattress protector. Available in Twin, Twin XL, Full, Queen, King, and California King sizes.
Brand: LUCID
Color: Blue Gel
Size: California King
Fabric Type: Memory Foam
Special Feature: Gel Memory Foam
Brand Name: LUCID
Age Range Description: Adult
Model Name: 4 Inch Gel Memory Foam Mattress Topper - Ventilated Design - Ultra Plush - California King
Number of Items: 1
Manufacturer: LUCID
UPC: 848971052013
Unit Count: 1 Count
Number of Packs: 1
Global Trade Identification Number: 13
Included Components: Mattress Topper
Item Weight: 27.9 pounds
Item Type Name: 4 Inch Gel Memory Foam Mattress Topper - Ventilated Design - Ultra Plush - California King
Model Number: LU40CK30GT
Manufacturer Part Number: LU40CK30GT
Manufacturer Warranty Description: 3-year warranty against manufacturer's defects.
Other Special Features of the Product: Gel Memory Foam
Closure Type: Pull On
Water Resistance Level: Not Water Resistant
Item Firmness Description: Ultra Plush
Fabric Type: Memory Foam
Product Care Instructions: Spot Clean Only
Material Type: Memory Foam
Size: California King
Color: Blue Gel
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Wednesday, Aug 26
Yes, absolutely! You may return this product for a full refund within 90 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Similar Products
Top Amazon Reviews
Size: King
Style: 4 Inch
Color: Blue Gel
So comfortable. A slight smell when I opened it but that went away quickly. Laid it out on the bed at like 8am and left it all day and have been sleeping on it for about a month now. We got the 4inch blue king, seriously like sinking into a cloud. My husband and I both fall asleep so fast, stay asleep better and have less aches. Its on top of a very firm hybrid mattress. It not as cooling as I thought but it is cooler than my mattress. Worth the money in my opinion.
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Reviewed in the United States on June 20, 2026 by Kelsay
Size: King
Style: 4 Inch
Color: Blue Gel
Absolutely LOVE this mattress topper! Purchased a new (expensive)mattress less than a year ago and have been having terrible issues waking up throughout the night with shoulder and hip pain (age related). I purchased the king size 4 inch memory foam. I chose to put this under our mattress pad (luckily my mattress pad has extra deep pockets and fits perfectly). I have finally slept throughout the entire night without any pain this past week! A total WIN for me! have just ordered another 4 inch one for our queen size bed for our RV! I can’t recommend this product enough! I had no issues whatsoever opening it up and letting it air out for 7 hours before putting on bed (maybe because it was a nice summer day….it unfolded itself without any assistance from me).
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Reviewed in the United States on July 23, 2026 by Rachael J. Nikkola
Size: Queen
Style: 4 Inch
Color: Blue Gel
Let me start off by saying this isn't a paid review. Memory foam's quality isn't just reliant on density. The measure of density of memory foam gives it a Ultra Plush/Plush/Medium Plush/Medium/Medium Firm/Firm/Extra Firm feel. In order for memory foam to BE plush, it has to be low density. The reason Tempur-Pedic doesn't offer low density memory foam (Tempur-ES 4.1 LB Foam & Original Tempur 5.3 LB Foam) is because they distinguish themselves that way. I've used Tempur-Topper Supreme (3" Tempur Original 5.3LB Memory Foam), and it's super high quality, but that Topper is meant for people who like firm mattresses, and I can say the same thing about the 3" Tempur-ES Memory Foam. I've flipped between this memory foam topper, and a Tempur-ES topper. The Tempur-ES is nice, and you can move around easier, but I never feel like I'm being cushioned and like I'm relaxed. You sink in to the Lucid 4" topper, and my body physically relaxes, and I feel cushioned. I wouldn't even go as far to say the Lucid 4" topper is plush, but in order to be a comfortable foam, you will have to sink in quite a bit, or else you're just laying on expensive concrete. Memory Foam is meant to be inexpensive - Memory Foam is cheap to make as they're basically just made of fossil fuels. Don't judge this topper by the price. I first tried a 3" Memory Foam Topper here on Amazon, since the topper had like a 4.9/5 on 100+ reviews, but I don't think that topper was memory foam, and was just basic polyurethane foam. The memory foam had no squishy feeling, and the imprint recovery was almost instant. The Lucid 4" Topper has a fairly slow recovery from imprint time given the Lucid Memory Foam's density. My parents back pains got better when I got them the 4" Lucid Topper. If you're a normal person, and you keep an open mind, then this Lucid 4" Memory Foam Topper is the best thing to make you sleep extra deeper, and sleep longer period or times. I went back to the Tempur-ES topper for 3 months, and that was the dumbest decision I've made in the past few years. My body oozes with relaxation and comfort on the Lucid 4" Topper now, of which never has happened w/ my Tempur-ES topper. Once you get the 4" Lucid Topper, be prepared to be hard to move around if you want to flip over in the middle of the night, but I flip positions 60-70% less w/ the Lucid Topper compared to the Tempurpedic-ES memory foam topper. I use the Lucid King Pillow hybrid as a pillow, the Lucid body pillow I hold on to w/ my arms when I lay on my side, and the basic Lucid memory foam pillow for in between my legs. The side sleep system I use is the best way to sleep. I do hear the Serta Perfect Sleep Luminous Plush Pillow Top is nice, but I can't imagine anything being more comfortable than the Lucid 4" Topper. Enjoy! -Andy R.
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Reviewed in the United States on January 26, 2022 by Amazon Customer
Size: King
Style: 4 Inch
Color: Blue Gel
About 14 years ago, we purchased a queen-size memory foam mattress (from Costco). It was our first time using a memory foam mattress, and we liked it a lot. Our next home came furnished with a new king bed, so we bought a 2-inch down-alternative mattress topper. It was inexpensive and adequately comfortable. Our home after that came with two new twin XL mattresses on a common frame (comprising an inexpensive equivalence to a king bed). We continued using our 2-inch down-alternative mattress topper. It finally became lumpy, so it was time to get something new. We saw the Lucid 4-inch memory foam topper and decided to give it a try. We find it to be a good product, providing comfort similar to an entire memory foam mattress (like the one we had originally). This topper even fills the small gap between the two twin mattresses, so that it feels like an actual king mattress. The topper is packaged well, and expanded to its full size in about 36 hours. At that time, the slight odor was gone too. We enclosed the mattresses and the topper in a basic mattress pad, and then put on the bed sheet. Inside a mattress pad and covered by a bed sheet, the topper is a bit less pliant than it is when uncovered, so it feels somewhat less cushy than it does on its own. You may or may not notice the difference, but that's purely subjective. We did not find the difference to be objectionable. Since this product is made in China, I was concerned about the chemical composition of the gas that the mattress gives off when it is new. The reason for my concern about this stems from contaminated Chinese drywall that was used in many homes in my area that were built between 2006 and 2008. The drywall gave off toxic gasses that caused health problems, and caused serious deterioration of copper, thus ruining wiring, air conditioning systems, and jewelry! I contacted Lucid customer support to inquire about this. They assured me that the gas given off by the mattress is harmless, but they were unable (or unwilling) to tell me the chemical composition of the gas. We paid $112.49 for the mattress, but less than a week later, Amazon was selling it for $89.99. At $112.49, this mattress topper is a good value. At $89.99, it's a steal! (By the way, if you do not like the topper and want to return it, keep in mind that after it expands to its full size, the topper will not even come close to fitting in the box in which it came.) Finally, our standard poodle agrees that this topper provides good bedtime comfort, and he approves, as shown in the photo!
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Reviewed in the United States on November 24, 2019 by J. Keller
Size: King
Style: 4 Inch
Color: Blue Gel
Absolutely totally impressed by Lucid’s customer service team!! Over the last 10 years or so, I have purchased 3, 4” toppers for my bed and 2 or 3 other mattress toppers (3” I believe)for other family members beds in my home. We have good mattresses, but the best way I have found to make them last COMFORTABLY longer is to put a memory foam mattress topper on them - As well as the fact that there is nothing better for a GREAT NIGHTS SLEEP than crawling and then up into a soft, comfy “feeling like you are sleeping on 12” of goose down comforters “ bed. Lucids’s 4” memory foam mattress does just that- makes your bed feel soft and warm and comfy a just as if you were sleeping on 12” of Goose down comforters! (Saying it’s like sleeping on a soft billowy cloud would be inaccurate- you’d fall through a soft billowy cloud & hit the ground like a brick. THAT doesn’t sound comfortable in the least!! 😂😂) So, if you like sleeping on a soft bed, the 4” is perfect!! So why is Lucid’s customer service so amazing? Well, just like every single other product in the world, occasionally one of those products will be defective or something just not right with it. It happens. No matter how great & amazing a company is, it’s pure naivety to believe that they will never ever have some sort of problem with one of the hundreds of thousands of individual products they sell. I don’t mean that every single one of a product they sell will have a problem, I am saying that 1 of the hundred thousands of one specific item will come off the factory floor as defective. In the situation I am referring to, that one item out of hundreds of thousands, happened to be the most recent of 3 of the 4” toppers I have purchased from Lucid. Building a great reputation for selling great products in various shapes and sizes is one thing. How your customer service department handles a situation when a customer contacts them saying that they are having problems with one of their products because that item is defective - THAT is how a company KEEPS their well earned great reputation. In full disclosure, I did have to contact them twice, but I honestly think that the first time I either put in the wrong reply email or the message portal on their website was not working properly- which honestly, with 99% of message portals and there being people writing about various things- compliments, curiosity and complaints as well as on occasion (yes it happens) competitors spamming message portals in an attempt to bog down customer service in order to make the department look ineffective, I personally think it’s better to just use the company’s customer service/information email, making sure that you write a brief description of your reason for contacting them IN ALL CAPS SO THAT THEY SEE IT PLAIN AS DAY! (Just a little advice from someone who has purchased far too many products online lol I am getting better at not doing that 😂😂 Anyways, customer service was amazing and went above and beyond. I emailed them explaining the problem, they wrote back requesting a couple pictures so they could see what I was explaining and to pass on those pictures to product quality control and then a reply stating that they had shipped me a replacement at zero cost to me. All within 3 days! Honestly, if I had sent pictures with my first email , it most likely would’ve been taken care of in one day, so the extra two days are on me! Thank you Lucid!! You have gained a loyal customer 😊
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Reviewed in the United States on August 11, 2025 by Burtice Wood
Size: Queen
Style: 4 Inch
Color: Blue Gel
This is the second memory foam topper i got and I am writing a review in case it helps someone. Because buying big bulky things and returning them is a pain in the butt so maybe this can help you in your buying decision. I am hunting for a topper a very hard, awful futon mattress that was advertised as 8" but was actually 3". I should have returned it right away but didnt' want to deal with return hassle (I learned my lesson now and regret that decision so much). I plan to chuck the whole futon in a year or two so I don't want to buy a new matress and am just looking for a topper to make it comfortable. A few weeks ago I got the linenspa 2" topper, and people wrote in reviews it was like sleeping on a cloud. I got it and was like what cloud? A concrete cloud? it was hard. Old me would have just suffered in silence, worried about the return process, but new me is like stop keeping things you don't love. And sleep is important. Returned that one, got this one in 4". I am 210 pounds now and 5'8 (gained weight post-Covid), an average looking albeit slightly tall woman, a size 14 hourglass (not apple) shape. My heaviest parts, like most people I guess are my hips/waist area. I am a side sleeper who cannot sleep on her back no matter what. THis grew to 4" with an hour, but I let it air out for over a day. i had chatted with lucid and they said waiting 2 days wasn't necessary. Cool! I put it on my bed (*good tip, btw, is I only put the fitted sheet over the topper, not the topper + mattress. so easy to make the bed) and tried to sleep in that night. The following happened each and every night I tried to sleep on it (i tested it for 3 nights): Sleeping on my side, my hips sunk down dramatically. Not all the way down to the mattress below it, but down significantly (I'd guess 2"?). Your body is absolutely not evenly supported (may be different if youre a back sleeper). Imagine your body jut being misaligned all night bc only your hips are sinking into a pit, but the rest of you is not sinking in. When I turned on my back I didnt seem to sink much at all but i just cannot sleep on my back. I feel like my muscles were fighting all night to just keep my body somewhat aligned and woke up feeling mildly like my muscles had been working all night, and not in a good way. I was not rested at all. Your spine, neck etc are supposed to be aligned when you sleep. With this topper, that is absolutely impossible at least for my body (and later, my husband's too, you'll see.) this happened each night (I did give it a few nights' test to give it a chance to see if anythng would change, before I unequivocally decided I need to get this out of the house.) I also woke up each night sweating. Hot. And When I wanted to get out of the bed to go to the bathroom, I had to like catapult myself out because I had sunken in. And if i wanted to flip from my left to right side, again, had to catapult. The absolute worst part is, I have felt completely dizzy (i put dizzy and dizziness in the headline so if anyone searches those words in reviews, like i did last night, it would show up) with my head spinning and like an electric shooting sensation in my right leg (edit/update: when i wrote the reivew, i hadnt returned it yet. i returned this i think over a week ago and still am having massive problems with my right leg which only started when i used this foam. i am now convinced i have a pinched nerve from this topper and am going to see a neurologist. the diziness ended the morning after we boxed this up to return it, but my leg issue persists- it's now weak, there's an electric shooting sensation, knee slightly bucking etc. ive never had a pinched nerve before but i looked it up and the symptoms match up) i have been dizzy only since I started using this to the point where I could not fuction rightly during the day. Felt crazy lightheighted and unable to focus, to the point where I was searching like mad last night "dizziness and memory foam" - turns out other people have reported this issue with memory foam in general. Look it up. Some people may not be as sensitive. I'm not a "everything must be natural" type but maybe i'll become one after this experience. (update: we packed it up for return after 3 days of using it and feeling dizzy - the morning after boxing it up, the dizziness was gone and has not returned.) My husband crawled into bed with me for a few minutes and we weigh about the same, so when our bodies were both sunken in at the same time, it wasnt as bad as when I was alone in it, with the matress sunken in all around me like i was in a sandpit. But i often sleep alone bc I snore :-) Last night he slept it in alone to test, and he didnt sleep all night. He sunk in too much and just couldnt sleep. He is about 5'11 205 pounds. That was good to know. I was going to return it anyway, whether he liked it or not, bc apparently my body can't handle memory foam at all, I cant let my body be dizzy and have weird neurological symptoms. But he woke up this morning and said "i dont like it. I couldn't sleep all night." I said why? He said he was sinking. But he was delirious from no sleep and went into the other zinus comofrtable bed to pass out, so I didn't get more info out of him. So I am done with memory foam for life and am going to line the top of my mattress with many, many blankets, if that doesn't work, I will try latex or wool. (edit: i tried topping my crappy mattress with many blankets and that didn't work. too hard and painful. next im going to try sheepskin and if that fails, latex.) Maybe you will have a different experience, if you're a back sleeper etc. I have read this memory foam is not high density so it's not supportive. Ive read some people love that sunken in feeling but I would caution, if only certain body parts or sinking in, it is really not good to spend 1/3 of your life in a misaligned position. I watch youtube videos for side sleepers and physical therapists and docs talk about the importance aligning our neck, shoulders, hips, and knees while youre laying down, the point of strategic pillow placement to make sure everything is aligned. This memory foam is not only not conducive to that, but actively hurts my alignment. Lastly, the return issue. I havent hit the return button yet but no mater how difficult it is to return, if you dont like something, you dont need to chuck it or live with it, aslong as you are in the return window. My husband and I will smoosh i down and roll it up and if it doesnt fit, will buy a bigger box and amazon can refund us for the box, but i bet it will fit in the original box. (update, it did. return process was great!!) Sleep is way to important to just "suck it up" - and it seems as though it is common for people to hav to try a few different toppers to find the one that is right for them (do you want 2,3,or 4"? latex? memory foam? wool? featherbed? soft, medium or hard?). It would be best to get a mattress that doesnt need a topper in the first place (I still love my zinus 10" we have in the other room!) but if youre like me with a weird matress situation I understad your plight. I hope this review helps someone. i know it's a hassle for both buyer and seller to mail and return these big bulky things so im trying to help people make decisions.
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Reviewed in the United States on December 24, 2023 by sunnydaysahead
Size: Queen
Style: 4 Inch
Color: Blue Gel
We have been very happy with this mattress topper. We laid it out in the guest room for about a week before putting it on our bed. It was fully expanded and no notable smell. It has been comfortable to sleep on, less waking up during the night.
Reviewed in the United States on August 9, 2026 by Lisa B.
Size: Full
Style: 4 Inch
Color: Blue Gel
UPDATED REVIEW 6-6-22 ***************************** I'm leaving my old review below, as for the 2st 4-5 nights, this gel foam topper was the best. But, since I'd been sleeping on a hard as a rock, large yoga mat for weeks prior to receiving the topper (see review for that) & an uncomfortable air mattress for weeks before that... that's probably the reason this topper felt like sleeping on a cloud. After 2+ wks of sleeping on this, I realized it's too soft to offer any support to spine/joints for me. I know others differ, which is why I left my previous review below. I'm a small girl, so I would guess the heavier you are, the less comfortable this will be in the way of offering good sleeping support for any length of time. To be clear, I don't have a mattress. I have cobbled together roll-up yoga mats, varying pieces (as I'll be moving in 6-mos & wanted to carry them with me in my car, rather than renting a trailer to move a mattress or leave another behind), which turned out to be a pricey mistake... if I just shelled out money for the firmer pillow-top, bed-in-a-box mattress I prefer (Ashley, sold her on Amazon at the best price), I wouldn't have the problem of nightly uncomfortable sleep & in fact, it would have cost far, far less. Lesson learned. In any event, after 3-wks, I wake up sore everyday & my spine feels like how a 90-yr old lady's must feel. I'm a side sleeper, so my hip is so sore, I can barely stand up & when I do manage to shimmy all over to actually get off the too-soft topper, I have severe low back pain, sciatica & walk hunched over, which lasts for an hour & I haven't had any of those since a car accident years ago. That's what's scared me the most... I'm afraid the sciatica/hip/back will worsen (it has worsened since day 1, in fact), so since I'm still in the return window, I am returning this topper tomorrow. It's great as a temporary bed, whether alone on a floor or placed on a bed frame. It's very bulky, but you could roll it up to place in a closet, if you have adequate room, although, you do need to let it puff up for 48-hrs once you unroll it again... given that, it's probably not the best choice as a guest bed, but your guests will sleep like babies for 3-4 nights. Kids could also sleep comfortably on it, especially if they're light weight. Note: Older folks or those with injuries will have a tough time getting off of it alone, cuz you do sink into it after hours of lying or sitting on it & since it's soft, you have no traction underneath as an aide in pushing yourself up. I'm a small girl & I struggle to find my way to the edge every morning. I have to roll around like John Belushi in Animal House doing the worm dance to find the edge, then roll out of bed. I've grown to really hate it & regret buying it. I've downgraded from 5* to 3 out of 5. It is comfortable, just not for very long. It is good quality, just not what I need. PREVIOUS REVIEW, WHEN I'D JUST RECEIVED THE TOPPER ******************************************************************* Best sleep ever. I resisted buying this as I've slept on guest beds with inches of corrugated foam toppers, which were so horrible, after day 2 of one 2-wk visit, I opted to sleep on the floor, much to my host's chagrin. I sunk into it like a victim from a horror film, it was so hot I was covered in sweat & felt liked I'd slept in a sauna, I kept waking up all night long & was so sunken in, getting out of a cartoonish bed of sponge felt like I needed a crane or 2 bodybuilder to assist me... & I'm a small girl. But, if you look at other reviews of mine, I'll briefly say that I needed a makeshift nest as I'm only in this apt in the middle of America for 6-mos & don't want to buy a mattress to leave behind. I travel & move often, so I've had to discard 6 mattresses in 5-yrs & my wallet is sparking curse words at me. My current set up is a full size, 3" thick, roll up, yoga mat, very well made, contents don't shift, but it's hard as a rock & not comfortable enough for side sleepers or for longer than 1-2 nights (see my review). To be fair, it's not meant to be a bed. No worries, I thought if it didn't work for sleeping, I could use it for exercise & I will once I move again. So, after 2 nights of feeling like I was sleeping on a hardwood floor, I then bought a dizzying array of various mattress pads, all claiming to be 4" thick, soft, fluffy as sleeping on a cloud... utter lies! Had to return all of them, even the ones in the $175 range... they all flattened & offered no cushioning. I finally settled on using 2 because I realized that not one of them offers enough cushioning. (To that end, one of the best & cheapest is good ol' Amazon basics.) Still, 2 mattress pads/toppers (feathers & fiber fill) on top of a hard as a rock mat, is not quite enough. Bought this gel foam topper after searching for wks. It was the best decision. It offers great cushioning, but I don't sink down to ridiculous proportions. A tip... let it lie unused for 48-hrs as the directions suggest. I was anxious to use it more quickly, but when I would lie down on it, I'd sink right in... it needs to puff up, firm up & settle & it does. I can't rave enough about it. Since I've been sleeping on it, I don't move around as much, I fall asleep right away, sleep soundly & don't wake up with all over body pain. Haven't had that in a long time. It's a wonderful product & worth every penny of the $100 I didn't want to spend... it was well worth it. 5* out of 5. A great product!!!
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Reviewed in the United States on May 23, 2022 by A Tabby in Curlers