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Zinus

ZINUS 5 Inch King Metal Smart Box Spring with Quick Assembly, Mattress Foundation, Strong Metal Frame, Easy Assembly

  • Based on 22,341 reviews
Condition: New
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Availability: In Stock.
Fulfilled by Amazon
Arrives Sunday, Apr 19
Order within 15 hours and 12 minutes
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Style: New/upgraded with quick assembly


Size: King


Features

  • Steel Interior Frame With Poly Jacquard
  • STRONG, DEPENDABLE, AND READY IN NO TIME - As if its ultra-durable steel structure and convenient packaging werent impressive enough, our original Smart BoxSpring has been given a quick-assembly upgrade
  • DURABLY ENGINEERED - Durable steel is used to construct the inside framework of this foundation; twin/twin xl sizes support a maximum weight capacity of 350 lbs, while all other sizes can support up to 700 lbs
  • EASIER THAN EVER ASSEMBLY - With fewer bolts and tool-free locking brackets for intuitive setup, assembly takes only minutes to complete
  • THOUGHTFULLY PACKAGED - All parts and instructions are packed into one compact box that ships straight to your door
  • Worry-free 5 year limited warranty included; box spring only, a bed frame or platform bed is required to support this foundation and is sold separately

Description

As the backbone for solid mattress support, a box spring that falls short can make or break your night’s sleep. We developed the Smart BoxSpring® with unbeatable durability and rock-solid stability to keep your mattress in shape for years to come. And our latest quick assembly version gives you total confidence when it comes to setup, requiring fewer bolts and ingeniously designed with easy to use, tool-free brackets. With our simple, step-by-step instructions on hand, you’ll have this foundation built and ready to use within minutes. Built with a strong and durable steel frame and a versatile poly jacquard cover that slips right on, the Smart BoxSpring® is the picture of dependability for any mattress. All packed in a compact shipping box with everything included, even our 5-year worry free warranty! Now that’s peace of mind you can sleep on.

Size: King


Material: Alloy Steel, Fabric


Product Dimensions: 78.7"L x 75.5"W x 5"H


Style: New/upgraded with quick assembly


Special Feature: Durable


Other Special Features of the Product: Durable


Included Components: Slat, Steel Frame, Cover


Brand Name: Zinus


Manufacturer: Zinus


UPC: 841550325300


Global Trade Identification Number: 00


Manufacturer Warranty Description: Worry-free 5 year limited warranty included.


Manufacturer Part Number: ZU-ABS-5KS


Model Number: ZU-ABS-5KS


Set Name: Zinus King Smart Box Spring with Quick Assembly


Item Type Name: Box Spring


Material Type: Alloy Steel, Fabric


Product Care Instructions: Wipe with Dry Cloth


Headboard Material: Fabric


Style Name: New/upgraded with quick assembly


Color: Grey


Finish Types: Steel


Furniture Finish: Alloy Steel


Form Factor: Rectangular


Shape: Rectangular


Compatible With Mattress Size: King


Maximum Weight Recommendation: 700 Pounds


Size: King


Item Dimensions L x W x H: 78.7"L x 75.5"W x 5"H


Item Weight: 42.78 Pounds


Ground To Item Distance: 5 Inches


Item Dimensions: 78.7 x 75.5 x 5 inches


Item Depth: 5 inches


Required Assembly: Yes


Assembly Instructions Description: Included


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Sunday, Apr 19

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

  • Klarna Financing
  • Affirm Pay in 4
  • Affirm Financing
  • Afterpay Financing
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  • Financing through Apple Pay
Leasing options through Acima may also be available during checkout.

Learn more about financing & leasing here.

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Top Amazon Reviews

    • Buy it!! So easy to assemble, very sturdy
Style: New/upgraded with quick assembly Size: Queen
Buy it, don’t hesitate. I chose the “New/upgraded with quick assembly” rather than “Original” option because easy assembly was important to me. I purchased the 5 inch box spring because I needed only a little lift for my queen mattress. This item is so perfect and SO easy to assemble! I got the box in the house alone and assembled it alone. Took 1 hour. The only hiccup was when I placed the middle connectors upside-down - make sure the holes are facing up only on the middle connector pieces marked “G” so that the middle rack can slide down into that slot. It’s a pain to disconnect if you place it wrong. The cover is so easy to get on, just like a fitted sheet. It did not slide off at all while placing the box spring onto the platform bed frame, which I also did alone. It doesn’t squeak or slide around. Love it!! ... show more
Reviewed in the United States on June 29, 2025 by DeAnne
    • Easy to assemble and well made
Style: New/upgraded with quick assembly Size: Queen
Easy to assemble picture directions I am 67 and I laid out all the pieces before I started . Just be sure to keep the sides marked “up” all up . The 8 screws are a little challenging because they use an Allen wrench and you can’t make a complete turn w it . However it’s easy to stand up on one end for better access to the screws . I was able to carry it into the bedroom by myself . Fit the queen bed frame fine . ... show more
Reviewed in the United States on November 19, 2025 by fla rt
    • Worth the price in a crowded field.
Style: New/upgraded with quick assembly Size: Queen
Fantastic box spring. The item is easy to assemble and comes together in well less than an hour. Clever pop in pieces and few bolts make for a sturdy bed frame. A hex wrench and a little socket hex wrench are included, though I couldn’t get the knack of using the socket hex wrench. The regular hex wrench was more than adequate .The cover is well made and fits well. Pleased with this purchase ... show more
Reviewed in the United States on June 10, 2025 by Becky B
    • Easy Assembly
Style: New/upgraded with quick assembly Size: California King
Easy to assemble. Sturdy. Only down side was the slats. Mattresses these days are made differently with foam, gel, etc so the slats don’t give total support. We had to add a thin plywood on top. Otherwise it works fine for our use.
Reviewed in the United States on March 14, 2026 by DKK
    • ZINUS 5 Inch Metal Smart Box Spring (Quality great!)
Style: New/upgraded with quick assembly Size: Twin
Review Image by Mina
The Sinus twin boxspring worked great for my needs at a good price in the size that I needed, 5 in. The quality is very good and sturdy and fits a twin frame perfectly. I plan on putting a air mattress on top of it for visitors. One piece was missing on the tip of a cross rod, lost in the shipment but the company responded quickly and replaced it immediately. Good customer service! Recommend buying this if you need a good twin box spring. Update 9-14-25. Twin box spring started collapsing periodically. Unfortunately I had to buy wood slats to support it so it wouldn't collapse. ... show more
Reviewed in the United States on March 23, 2024 by Mina
    • Fraud/scam
Style: New/upgraded with quick assembly Size: Queen
DO NOT BUY FROM ZINUS. THEY ARE A SCAM. I bought 2 frames 2 years ago got my 7 years old, 40lbs daughter. When a plastic connector broke, I contacted them trying to buy the plastic part. They said they don’t sell that key but frame odds under warranty so they will take care of it. A month of later, they say that the part that broke was not an original factory last (as though I’m upgrading plastic connectors). Fraud alert. DO NOT BUY ... show more
Reviewed in the United States on December 5, 2025 by Amazon Customer
    • 5 stars
Style: New/upgraded with quick assembly Size: Queen
Very nice box springs easy assembly recommended
Reviewed in the United States on February 18, 2026 by JM
    • Box spring
Style: New/upgraded with quick assembly Size: Full
Super easy to put together. Comes with a tool to use. Only had to screw in eight screws. Size is great. Looks good. I’d recommend
Reviewed in the United States on January 18, 2026 by Sarah proeschel

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