Is this a real box spring with springs?

No. It is a steel-frame foundation with a fabric cover. It adds firm, flat support rather than bounce.

What mattress types does it suit?

It works with memory foam, latex and hybrid mattresses. Innerspring owners who want give should look at a sprung box spring instead.

It is 5 inches tall, so it raises the mattress less than a standard 9-inch box spring. That suits low beds and platform frames.

How long does assembly take?

Zinus says minutes, and owners report a short build with the tool-free brackets. A king is easier with two people.

The frame parts, brackets, cover and instructions, all in one compact carton. No tools are needed.

Does the warranty cover squeaks?

The 5-year warranty covers manufacturing defects. Normal wear and loosening bolts are usually not covered, so check and retighten the brackets.

What do buyers say about the Zinus 5 Inch King WonderBox Smart Box Spring?

Rated 4.3 out of 5 from 6 ratings.

Where can I buy the Zinus 5 Inch King WonderBox Smart Box Spring?

2 stores we checked sell it, including Walmart, Amazon.

Zinus 5 Inch King WonderBox Smart Box Spring

Best price now

$109.99at WalmartChecked Nov 12

Compared across 2 stores. Prices are checked against each store and labelled with when.

Visit Walmart

Zinus 5 Inch King WonderBox Smart Box Spring

Best price now

$109.99at WalmartChecked Nov 12

Compared across 2 stores. Prices are checked against each store and labelled with when.

Visit Walmart

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Price facts

Last seen at $109.99 at Walmart on Nov 12.
Checked at 2 stores.

Our take on the Zinus 5 Inch King WonderBox Smart Box Spring

The Zinus WonderBox Smart Box Spring is a 5-inch king foundation with a steel frame and a gray poly jacquard cover. It ships compact in one box and assembles with tool-free brackets and fewer bolts than earlier Zinus box springs. The low 5-inch height suits platform beds, low-profile frames and sleepers who want a firm, quiet base under a memory foam or hybrid mattress. It is a basic foundation rather than a sprung box spring, so it adds firmness, not bounce.

Best forLow-profile bed frames and platform bedsMemory foam and hybrid mattressesShoppers who want tool-free assemblyGuest rooms and rentals

Pros

Steel frame with a fitted jacquard cover
Tool-free brackets and fewer bolts for quick setup
Ships compact in one box with all parts included
5-year warranty
Low 5-inch height keeps the bed close to the floor

Cons

Firm, rigid base with no spring give
Some owners report squeaks and creaks over time
Assembly still takes two people for a king
Cover can be tight to pull over the frame

Zinus 5 Inch King WonderBox Smart Box Spring prices at every store

WalmartNew
In stockSold by SuperordinaryReturns: Sold by a Walmart Marketplace seller; returns go to the seller under the seller's returns policy.
$109.99Free shippingChecked Nov 12
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AmazonNew
Availability unknown
As an Amazon Associate, Deal.ai earns from qualifying purchases.
$132.99Free shippingChecked Nov 12
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Zinus 5 Inch King WonderBox Smart Box Spring price history

Lowest price we've seen: $132.99 on Nov 12 at Amazon. Tracked across 1 store since Nov 12.

What reviewers say

Owners generally find the WonderBox sturdy and easy to put together for a boxed foundation, and it holds up under foam mattresses. The main complaints are noise after months of use and a stiff, unforgiving feel.

What people mention

AssemblyPraisedOwners say the tool-free brackets and clear steps make setup quick for a boxed foundation.
NoiseCriticisedSome owners report squeaks and creaks after a few months of use.
SupportPraisedReviewers say it gives firm, even support under foam and hybrid mattresses.
FirmnessMixedThe rigid steel frame is stable but gives no spring, which some sleepers dislike.
PackagingPraisedBuyers like that the whole foundation arrives in one compact box that fits upstairs.

About the Zinus 5 Inch King WonderBox Smart Box Spring

The Zinus 5 Inch King WonderBox Smart Box Spring is a mattress foundation that supports a mattress and helps keep it in shape. It has a steel frame and a poly jacquard cover that slips on.

This is the quick assembly version. It uses fewer bolts and tool-free brackets. Step-by-step instructions are included, and the foundation can be built within minutes.

It ships in a compact box with everything included.

Size: King
Height: 5 inches
Color: Gray
Frame: Steel
Cover: Poly jacquard, slips on
Assembly: Quick assembly with fewer bolts and tool-free brackets; step-by-step instructions
Warranty: 5 years

Specifications

bed_size: KingSource
color: GraySource
actual_color: GraySource

Questions and answers

Is this a real box spring with springs?: No. It is a steel-frame foundation with a fabric cover. It adds firm, flat support rather than bounce.
What mattress types does it suit?: It works with memory foam, latex and hybrid mattresses. Innerspring owners who want give should look at a sprung box spring instead.
How tall is it?: It is 5 inches tall, so it raises the mattress less than a standard 9-inch box spring. That suits low beds and platform frames.
How long does assembly take?: Zinus says minutes, and owners report a short build with the tool-free brackets. A king is easier with two people.
What is in the box?: The frame parts, brackets, cover and instructions, all in one compact carton. No tools are needed.
Does the warranty cover squeaks?: The 5-year warranty covers manufacturing defects. Normal wear and loosening bolts are usually not covered, so check and retighten the brackets.
Where is the Zinus 5 Inch King WonderBox Smart Box Spring cheapest?: At Walmart, for $109.99, as of our latest check.
What do buyers say about the Zinus 5 Inch King WonderBox Smart Box Spring?: Rated 4.3 out of 5 from 6 ratings.
Where can I buy the Zinus 5 Inch King WonderBox Smart Box Spring?: 2 stores we checked sell it, including Walmart, Amazon.