Serta Perfect Sleeper X Quilted Hybrid Knox Firm 13.5 Inch Mattress on a modern wood bed frame. Perspective view of Serta Knox Firm 13.5 Inch Quilted Hybrid Mattress with a decorative floral cover. Front view of Serta Perfect Sleeper X Knox Firm mattress featuring cooling and 5-zone support labels. Top view of the breathable floral quilted cover on the Serta Perfect Sleeper X Knox Firm mattress. Profile of the 13.5 inch Serta Knox Firm mattress featuring a durable dark grey quilted border. Close-up of Serta Perfect Sleeper X branding on the Knox Firm 13.5 inch hybrid mattress corner. Knox Firm mattress diagram showing 5 ZoneActive support, cooling tech, and hybrid comfort layers. Serta Knox Firm mattress comfort scale showing firm support ideal for back and stomach sleepers. Serta mattress layers diagram showing firm zoned support and advanced cooling technology.
Serta Perfect Sleeper X Quilted Hybrid Knox Firm 13.5 Inch Mattress
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Serta Perfect Sleeper X Quilted Hybrid Knox Firm 13.5 Inch Mattress

$1,099.00
$1,499.00
Save $400.00
Brand: Serta
Size
i Size Guide
$1,099.00
Only 17 left in stock
Free USA Wide Delivery Free USA Wide Delivery
10 Year Warranty 10 Year Warranty
Advanced Technology Advanced Technology

To begin with, the Serta 13.5-inch hybrid queen or king welcomes you with a cool-touch quilt that stays fresh to the skin. Next, layers of graphite memory foam and Cool Twist® Gel Memory Foam redistribute heat, giving you cool-to-the-touch comfort even in warmer rooms. 

Beneath the quilt, plush yet firm transition foams pair with a five-zone coil band to create targeted spinal alignment that many owners call the best 13.5-inch firm mattress for back pain. Deeper down, 920-count individually wrapped coils supply dynamic push-back and minimize partner motion, turning this bed into a true Serta hybrid mattress with pocketed coils for undisturbed sleep for couples. 

Finally, you can buy Serta Knox Firm online today, enjoy free shipping in the USA and quick 1–2 week delivery, and lock in a hefty discount while stock lasts.

Firm Zoned Support for Alignment

Five targeted zones keep the shoulders, hips, and lower back level for healthier posture

Hybrid Pressure-Relief System

Graphite memory foam cradles curves without sacrificing the solid lift back sleepers need

Advanced Cooling Technology

Gel and graphite foams move heat away, helping hot sleepers stay comfortable

Motion Isolation for Couples

Individually wrapped coils absorb movement so partners sleep through the night

Excel-Inspired Edge Stability

Reinforced perimeter prevents sag and lets you use the entire surface

Sale + Financing Flexibility

Save $600 now and split payments over time for easy ownership

Key Mattress Benefits

Serta Perfect Sleeper X Quilted Hybrid Knox Firm 13.5 Inch Mattress

6 Layers
Of Cooling
Comfort

Soft knit infused with cooling fibers delivers an immediate refreshing sensation.

Dual-action foams pull heat away and relieve pressure while maintaining the mattress’s luxury firm support feel.

Extra-dense strip beneath the hips bolsters alignment and extends durability.

Balanced layers distribute weight evenly and resist long-term body impressions.

Pocketed springs adapt independently for motion control, while a fortified perimeter stops edge sag.

Firm bottom foam anchors the coil unit for years of reliable performance.

Serta Perfect Sleeper X Quilted Hybrid Knox Firm 13.5 Inch Mattress
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WE'VE GOT ANSWERS
HAVE QUESTIONS?

WE'VE GOT ANSWERS

Designed for deep comfort and better rest, so you wake up refreshed and ready for the day

Yes. Zoned coils and firm foams keep the spine neutral, which many back and stomach sleepers prefer.

No. Any solid platform, slatted base with gaps under three inches, bunkie board, or adjustable frame provides proper support; a box spring is optional.

Perfect Sleeper X models feature a cool-touch quilt, graphite memory foam, and a five-zone support band for enhanced cooling and alignment versus the standard Perfect Sleeper line.

Cloudy Mattress rates it Firm Comfort, offering sturdy lift with minimal give.

The product page does not specify certification. Serta typically uses foams that meet U.S. safety standards; contact Serta for official CertiPUR-US documentation.

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