This replacement comfort foam layer is the medium-firmness foam that sits on top of the air chambers in a Sleep Number® FlexTop King bed — the layer that gives the surface its feel. It is our closest match to the original regular foam, so it brings an older bed back to how it felt when it was new. Replacing it eliminates body impressions and sagging and restores the supportive, cradling feel, without touching the air chambers, pump, or cover you already own. Made in the USA and CertiPUR-US® tested.
FlexTop King
Medium feel
1.8 lb density
35 ILD firmness
1"–4" thickness
CertiPUR-US® tested
What size is this? FlexTop King explained
This is made for the FlexTop King. It is one solid King-size foam layer (76" × 80") with a 34" cut from the center of the head running toward the middle, which lets the two heads of the bed raise independently on a FlexFit adjustable base. Even with that head cut, the foam is a single piece with one uniform feel across the whole surface. Choose your height below.
Is your FlexTop bed built from two separate Twin XL pieces?
Some FlexTop beds use two separate Twin XL foam layers (38" × 80" each) instead of one solid piece with a head cut. If that is how yours is built, order two Twin XL layers from our standard medium regular foam instead. Two separate Twin XL pieces is also the only way to set a different feel on each side of a FlexTop bed. Not sure which you have? Browse our standard foam collection or call us at 610-327-2322.
What this foam feels like
This is a true happy-medium feel: firm, even support without sinking or bottoming out, and without the hard, boardy feeling of a foam that is too firm. At 1.8 lb density and 35 ILD it is the most comparable feel to Sleep Number original regular foam.
If your bed sags or has body impressions and you want to firm it back up, this is the foam most people should choose. It restores solid, even support — and because you have a Sleep Number bed, you can dial the air chambers firmer on top of it for as much added support as you want. Only if you specifically want an extremely hard, board-like surface should you look at our firm regular foam (50 ILD), which most people find too firm for everyday comfort.
Which thickness should I choose?
The thickness you pick sets how much cushioning sits over the air chambers, and it also affects your shell height. Most beds use a 2" or 3" comfort layer. Match the thickness you have now to keep the same feel and shell height, or go thicker for more cushioning (which raises your shell height by the difference, so order a cover to match if you are replacing that too).
Not sure how thickness ties into shell height? Our guide to measuring your Sleep Number bed walks through it, or call us at 610-327-2322.
Specifications
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Fits: Sleep Number FlexTop King (solid King foam with 34" center head cut)
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Feel: medium — closest match to Sleep Number original regular foam
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Density: 1.8 lb
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Firmness: 35 ILD
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Thickness options: 1", 2", 3", or 4"
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Quality: CertiPUR-US® tested, made to order in the USA
Compare our FlexTop King foams
All of these are cut for the FlexTop King. Here is how the feels compare so you can pick the right one:
| Foam |
Feel |
Firmness |
Best for |
| Soft Regular |
Plush, sink-in |
12 ILD |
Softening a bed that feels too firm |
|
Medium Regular (this page) |
Balanced, original feel |
35 ILD |
Most people; firming up a sagging bed (closest to original) |
| Firm Regular |
Extra-firm, little give |
50 ILD |
Sleepers who want a very hard surface |
| Gel Memory |
Contouring, cooler, sink-in |
Medium (cradle) |
Pressure relief; plush premium feel |
| Latex |
Buoyant, responsive, on-top |
29 ILD (medium) |
Lively support; durable upgrade (not a Sleep Number foam) |
| Egg Crate |
Light cushion + airflow |
35 ILD |
Economical comfort and cooling boost |
Will this fit my bed?
This is made to order for the FlexTop King split-head configuration. If your bed's foam side rails have also softened, you can rebuild the firm edge at the same time with the FlexTop complete rail set. Browse everything for your bed in our FlexTop Split-Head collection, or see the full Sleep Number repair parts collection.
Frequently asked questions
What does this foam do?
It is the comfort layer that lays on top of the air chambers and gives the bed its surface feel. Replacing a worn comfort layer removes body impressions and sagging and restores the supportive, cradling feel of a newer bed.
How does this compare to Sleep Number original foam?
It is our closest match to the original regular foam — a medium feel at 1.8 lb density and 35 ILD. It supports you without bottoming out and without feeling hard or boardy.
I want to firm up a sagging bed — is this the right foam?
For most people, yes. This medium foam restores firm, even support and matches the original Sleep Number feel, and you can adjust your air chambers firmer for extra support on top of it. Our firmest foam is an extremely hard, board-like surface that most people find too firm, so for everyday firming-up this medium is the right call.
Is this one solid piece or two?
It is one solid King-size piece with a 34" cut at the center of the head so the two heads raise independently, giving one uniform feel. If your bed instead uses two separate Twin XL pieces, order two Twin XL layers from our standard medium foam page.
What thickness should I order?
Match the thickness of your current comfort foam to keep the same feel and shell height; most beds use 2" or 3". Going thicker adds cushioning but raises your shell height by the difference, which matters if you are also replacing the cover.
What if the foam is too firm or too soft?
No problem — we offer a 30-day comfort exchange. Return it for a full refund or credit, or keep it and take a one-time 50% off a replacement (most people choose this — nothing to ship back). See our Foam Comfort Exchange & Return Policy for full details.
