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FATHOM

FATHOM Firm King Mattress 12 Inch Memory Foam Mattress King Size Bed in a Box for Back Pain Relief and Cool Sleep with Gel Foam and Removeable Fiberglass Free Cover, CertiPUR-US Certified

  • Based on 282 reviews
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Availability: In Stock.
Fulfilled by Amazon
Arrives Thursday, Jun 4
Order within 15 hours and 27 minutes
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Size: King (U.S. Standard)


Style: 12 Inch


Pattern Name: Firm


Features

  • Advanced Cooling Comfort: The AeroFusion gel memory foam mattress ensures exceptional breathability and heat dissipation, adapting precisely to your body's contours while resisting temperature sensitivity. Enjoy cool, cradling comfort no matter the season.

Brand: FATHOM


Size: King (U.S. Standard)


Product Dimensions: 80"L x 76"W x 12"Th


Item Weight: 85 Pounds


Item Firmness Description: Firm


Top Style: Gel Top


Cover Material: Polyester


Number of Layers: 3


Fill Material: Gel Memory Foam, Memory Foam


Weight Limit: 750 Pounds


Item Firmness Description: Firm


Number of Layers: 3


Weight Capacity Maximum: 750 Pounds


Additional Features: Breathable, Durable, Low Motion Transfer, Pressure Relief, Temperature Regulating


Construction Type: Memory Foam


Size: King (U.S. Standard)


Item Dimensions L x W x Thickness: 80"L x 76"W x 12"Th


Item Weight: 85 Pounds


Item Thickness: 12 Inches


Item Dimensions: 80 x 76 x 12 inches


Item Depth: 12 inches


Cover Material: Polyester


Fill Material: Gel Memory Foam, Memory Foam


Mattress Comfort Layer Material: Comfort Foam, Gel Memory Foam


Material Type: Gel Foam


top-style: Gel Top


Color: Firm


Style Name: 12 Inch


Brand Name: FATHOM


Model Name: Fathom Firm 12" K


Product Benefits: Back Pain Relief, Improves Sleep, Posture Support, Pressure Relief, Stress Relief


Model Number: Firm 12 K


UPC: 840418683927


Mattress Type: Standard Mattress


Manufacturer: FATHOM


Set Name: FATHOM Firm King


Manufacturer Part Number: FA12KFRT


Included Components: Memory Foam


Age Range Description: Adult


Item Type Name: Bed Mattress Conventional


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Thursday, Jun 4

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.

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Top Amazon Reviews

    • Definitely comfortable for the price!
Size: Queen (U.S. Standard) Style: 12 Inch Pattern Name: Firm
Review Image by ThePhoenix
Review Image by ThePhoenix
Review Image by ThePhoenix
So where to begin, we have been in search for over a year now for a replacement mattress that is firm but comfortable to help alleviate sciatic back aches. We have tried several brands ranging from expensive to avg price. All returned back because they either weren't firm as stated and didn't help with back aches. Finally decided to try this Queen mattress, after researching and reading reviews/videos etc... you name it! OMG, if you are in search for a true firm mattress this is it! I was hesitant because I never had heard of this brand and at a lower price range (on sale), but even at regular price it's truly great quality & value. Now after having it for a few months, I can happily say that my hubby no longer feels aches and we both feel rested in the mornings. Best part it had No odor, expanded rapidly, and we were able to sleep on it after waiting 24 hrs. We opened it in our living room area as we didn't think it would expand so rapidly but was pleasantly surprised that it did, see pics, and that was not even after 2 hrs. On a different note, it took me maybe 2 weeks to adjust since it's definitely firmmer than the mattresses I had in the past. The good thing is that adding a memory topper would help if necessary. So far, I am really happy with the purchase and glad I took the leap in getting it! The cover is made of high quality material has a zipper for easy washing. ... show more
Reviewed in the United States on March 13, 2026 by ThePhoenix
    • Compact Delivery, Big Comfort and Support!
Size: Queen (U.S. Standard) Style: 10 Inch Pattern Name: Firm
I am extremely impressed with this memory foam mattress! It has the perfect firm support—just what I needed for a restful night’s sleep. The quality is outstanding: it feels sturdy yet comfortable, contouring to my body without feeling too soft. I’ve noticed less back discomfort since I started using it. Breathable and well-made materials, it doesn’t trap heat, so I stay cool all night. 😊 The mattress arrives in a compact box, maaking it easy to carry. Easy to set up, it inflates right away and holds its shape beautifully. Definitely worth every penny for anyone looking for a firm, supportive, and long-lasting mattress. ... show more
Reviewed in the United States on April 1, 2026 by Emma B
    • Sturdy, Easy to Use, and Great Support
Size: Twin Style: 8 Inch Pattern Name: Firm
I was pleasantly surprised by how comfortable this mattress is, especially for the price. It expanded well after opening and was very easy to set up. The firmness feels supportive without being too hard, and the gel memory foam gives it a nice cushioned feel. It sleeps cooler than I expected and works great for a child’s room, guest room, or everyday use. I also like that the cover is removable and fiberglass-free. Overall, this is a great twin mattress that feels well made and comfortable for a good night’s sleep. ... show more
Reviewed in the United States on March 31, 2026 by Brittany Correa
    • Perfect for back pains
Size: Queen (U.S. Standard) Style: 12 Inch Pattern Name: Firm
I recently purchased this Firm Queen 12-Inch Memory Foam Mattress, and I’m very impressed with its quality and comfort. The mattress arrived quickly and was easy to set up right out of the box. It expanded to its full 12 inches within a few hours. The firmness level is perfect for anyone who needs extra support, especially for back pain relief. I’ve noticed a significant improvement in my sleep quality, and I wake up with less stiffness in my back. The gel foam layer keeps the mattress cool throughout the night, which is a big plus for me as a warm sleeper. ... show more
Reviewed in the United States on February 28, 2026 by Y Review
    • Great Value, Great Sleep
Size: Full Style: 10 Inch Pattern Name: Firm
If you’re looking for a very firm, but comfortable mattress, this is it. It’s firm, but it has a soft top layer for comfort. I didn’t know if I was going to like it in the beginning because it was so firm, but I’ve had it for almost a month and I’ve gotten the best and deepest sleep I’ve ever had. Highly recommend! Doesn’t have an odor either. Seems very durable and is a great value for the money. Didn’t take very long for it to inflate to full size, making it easy to use. ... show more
Reviewed in the United States on March 15, 2026 by BD
    • Incredible. Best firm mattress
Size: King (U.S. Standard) Style: 10 Inch Pattern Name: Firm
This mattress is incredible. We both still love it after a couple months of use. It’s the only firm mattress we were able to find (without spending like 6k). I think this is much more comfortable than the $8,000 tempur-pedic ones we tested in-store. You don’t sink in at all, and it gives great support, but is still comfortable (so you don’t feel like you are on a hardwood floor or something; it’s still soft, just doesn’t squish down or compress). ... show more
Reviewed in the United States on March 15, 2026 by Amazon Customer
    • Very good mattress
Size: King (U.S. Standard) Style: 12 Inch Pattern Name: Firm
I had a Sleep Innovations for many years. A few in fact. I was setting up a new house. They don't seem to be around as much so I thought I would try this. Same price point. The mattress is very firm so far which I like. It had a slight odor to it when it was first opened. I let it breathe and opened a window. It did go away quickly. For the money it is a good mattress. Time will tell if it holds it firmness. Stitching is not perfect but that won't affect the sleeping. ... show more
Reviewed in the United States on March 25, 2026 by genius
    • Actually firm as advertised
Size: Queen (U.S. Standard) Style: 10 Inch Pattern Name: Firm
So after sleeping on a uncomfortable mattress that i also bought on amazon for months, this is literally the best mattress i have ever slept on in my entire life. It is literally so firm, my back doesnt ache, my hips dont ache, and best part i dont toss and turn as much. This mattress will probably cost you twice the amount anywhere else, this is a great price for the quality. Im in love, its been so hard to get up its just that comfortable. 1000/10 easy to set up, was ready to go after letting her do her thing for an hour or two. Thank you Fathom!! ... show more
Reviewed in the United States on March 11, 2026 by Lana Vindel

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