These replacement foam side rails restore the firm, supportive edge on a Sleep Number® bed — the foam border that runs along each long side of the mattress and keeps the surface from collapsing when you sit or sleep near the edge. They are made to order in the USA at a higher density than the originals, so the seating edge feels firmer and lasts longer. This listing is the pair: two rails, one for each side of the bed.
2.6 lb density
85 ILD firmness
4" wide each
6" or 7" height
Made to order, USA
Why replace your foam side rails?
The side rails are what give a Sleep Number bed its edge support. Over the years they soften and break down, and that is when the sides of the bed start to feel weak — you sink at the perimeter, the seating edge gives way when you get in or out, and it can feel like you might roll off. Replacing the rails brings that firm border back without touching the air chambers, pump, or cover you already own.
Ours are built firmer than the factory rails: a 2.6 lb foam density at 85 ILD, which is a measure of how much the foam resists compression. The result is a more stable seating edge and a perimeter that holds up to daily use.
Do you need the Pair or the Complete Set?
This listing
Pair of Side Rails
Two rails for the long left and right sides of the mattress. The right choice when the sides have softened but the head and foot are still fine.
Upgrade
Complete Set
All four rails — both sides plus the head and foot — for a full perimeter rebuild, with an optional center rail. See the Complete Set →
Specifications
-
Density: 2.6 lb — higher than the original rails
-
Firmness: 85 ILD for a firm, stable seating edge
-
Each rail: 4" wide, in the length that matches your size
-
Height options: 6" or 7" — match this to your existing rails
-
Made to order in the USA to fit your size and height
Sizes & measurements
Each rail is 4" wide and built in the length below; you choose the height (6" or 7") to match what is in your bed now.
| Size |
Each rail (W × L) |
| Twin |
4" × 75" |
| Twin XL |
4" × 80" |
| Full |
4" × 75" |
| Queen |
4" × 80" |
| King |
4" × 80" |
| California King |
4" × 84" |
| Expanded Queen (66" × 80") |
4" × 80" |
| RV King (72" × 80") |
4" × 80" |
Not sure which height you have? Our guide to measuring your Sleep Number bed walks through it, or call us at 610-327-2322 and we will confirm it with you.
Will these fit my Sleep Number bed?
Because every rail is made to order, we fit older beds, newer smart-bed models, and sizes the manufacturer no longer sells — including Expanded Queen and RV King. If your sides sag but the foam comfort layer on top has also softened, many owners refresh both at once; you can add a matching replacement comfort foam layer while you are here. Browse everything on our Sleep Number foam & rails page or the full Sleep Number repair parts collection.
Frequently asked questions
What are foam side rails on a Sleep Number bed?
They are the firm foam borders that run along each long side of the mattress, inside the cover and around the air chambers. They provide the edge support that keeps the perimeter of the bed from collapsing when you sit or sleep near the edge.
How do I know if my side rails need replacing?
The most common signs are soft or sagging sides, a seating edge that gives way when you get in or out of bed, and the feeling that you might roll off the edge. If the middle of the bed is fine but the sides have gone soft, the rails are usually the cause.
Does this listing include all four rails?
No — this is the pair, which replaces the two long sides. If you also need the head and foot, choose the Complete Set, which includes all four rails and an optional center rail.
What height should I order?
Match the height of the rails already in your bed — most are 6" or 7". If you are changing the feel of the bed or are unsure, measure your current rails or call us and we will help you choose.
How do these compare to the original Sleep Number rails?
They are firmer. At 2.6 lb density and 85 ILD, they give a more supportive seating edge than the factory rails and are built to hold up longer.
