Best for: Back sleepers wanting a trusted-brand bolster
The back-sleeper bolster from the category's bestselling brand — a memory-foam half-cylinder that props the knees to relieve the lower back.
This is ComfiLife's answer for back sleepers: a memory-foam bolster that sits under the knees to keep them gently bent, flattening the lumbar arch and taking load off the lower spine. Same trusted ComfiLife foam and washable cover as their side-sleeper contour, just shaped for lying on your back — and useful under the ankles for leg elevation too. It's a straightforward, well-made bolster at a fair price. Like all under-knee pillows it's back-sleeping only, and its single loft won't suit everyone, but for lumbar relief from a brand people already trust it's an easy pick.
Prices shown were last checked on 2026-10-11 and can change at any time — the price on the retailer's site at checkout is the one that applies. Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product. As an Amazon Associate and affiliate we may earn a commission on purchases made through these links, at no extra cost to you.
We show the price at our recommended retailer as at our last check of that offer (2026-10-11) and the manufacturer's list price for comparison. Amazon prices come from Amazon's own product data service and are refreshed twice a day; each one shows the date and time Amazon gave it, and one older than 24 hours is replaced by “Check price”. Other retailers' prices are checked by hand and show the date of that check. Retail prices move constantly, so the price on the retailer's own page at checkout is the one that applies. More on Amazon prices
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How our 8.2/10 breaks down — rated on the dimensions that matter most for knee pillows, from published specifications and third-party test data, not the marketing.
Featured in our guides
Quick verdicts for the knee pillows most often considered alongside the ComfiLife Knee Bolster for Back Sleeping.
The back-sleeper's pick — an under-knee bolster that lets the knees bend to flatten the lumbar arch, and the highest-rated pillow here.
→ Back sleepers with lower-back pain
The low half-moon bolster — a subtler under-knee lift for back sleepers who find full bolsters too tall, at a friendly price.
→ Back sleepers who want gentle, low lift
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Both are back-sleeper under-knee bolsters. Everlasting Comfort rates a touch higher (4.5) with a cool-touch cover; the ComfiLife bolster comes from the category's bestselling brand and doubles for leg elevation. Near-tie — pick on cover feel and price.
Same brand, opposite sleepers. The bolster goes UNDER the knees for back sleeping; the hourglass knee pillow goes BETWEEN the knees for side sleeping. Choose by how you sleep.
Yes — propped under the calves or ankles it works as a leg-elevation wedge for circulation or swelling, not just under the knees for back support.
It uses ComfiLife's dense memory foam, which holds its shape and lift better overnight than the soft foam in cheap bolsters that flatten by morning.