Skip disability assistance statement.

Welcome to our website! As we have the ability to list over one million items on our website (our selection changes all of the time), it is not feasible for a company our size to record and playback the descriptions on every item on our website. However, if you have a disability we are here to help you. Please call our disability services phone line at 636-583-3133 during regular business hours and one of our kind and friendly personal shoppers will help you navigate through our website, help conduct advanced searches, help you choose the item you are looking for with the specifications you are seeking, read you the specifications of any item and consult with you about the products themselves. There is no charge for the help of this personal shopper for anyone with a disability. Finally, your personal shopper will explain our Privacy Policy and Terms of Service, and help you place an order if you so desire.

4.6 | 142 Reviews

Perfect Sleeper X Knox 13.5" Hybrid Firm Mattress -King

Perfect Sleeper X

Features

  • Our 5 ZoneResponse™ Design combines coils and contouring memory foam for full body spinal alignment
  • Our PerfectConform™ Memory Foam contours and cradles your pressure points for rejuvenating sleep
  • CoolFeel™ System - Cooling technology keeps you comfortable throughout the night
  • CertiPUR-US® Certified

Quick Specs

  • Brand: SERTA
  • Line: Perfect Sleeper X
  • Type: Tight Top
  • Width: 13.5"
  • Height: 76"
  • Depth: 80"

See More

 
Experience premium support and perfect sleep with our new Serta® Quilted Perfect Sleeper X™ Collection. Our 5 ZoneResponse™ Design is comprised of Perfect Conform™ Memory Foam paired with 5-zoned coils for full-body alignment. Sleep comfortably cool throughout the night with cooling technology and graphite-infused memory foam designed to redistribute heat away from your body. A quilted top offers a classic feel and added layer of plush foam. Xtraordinary sleep is possible, with Serta® Quilted Perfect Sleeper X™.

Features

  • Our 5 ZoneResponse™ Design combines coils and contouring memory foam for full body spinal alignment
  • Our PerfectConform™ Memory Foam contours and cradles your pressure points for rejuvenating sleep
  • CoolFeel™ System - Cooling technology keeps you comfortable throughout the night
  • CertiPUR-US® Certified
  • Designed and Built in USA
  • Adjustable Friendly
  • 10 Year Warranty
  • Your new mattress may initially feel firmer than expected. Please allow up to 60 days to acclimate to your new mattress as it naturally adjusts to contour, comfort, and support you best
  • Firm - Ideal for stomach and back sleepers with extra support
  • Premium memory foam is temperature-sensitive; it may feel firmer in cooler temperatures and softer in warmer ones. For your preferred comfort, please allow several hours for your memory foam mattress to adjust to the room's temperature
Brand Serta
Manufacturer Name Serta Simmons Bedding LLC
UPC 198167021393
Computed Mattress Size King
Country of Manufacture USA
Assembled in USA? Yes
Computed Product Type One Sided Mattress
Product Category Mattress
Family Name Perfect Sleeper X
SubFamily Name Knox
Mattress Top Type Tight Top
Mattress Type Hybrid
Product Type Mattress
Year of Launch 2024
Dealer Line National Line
Layer 1 Material Firm HD Foam
Layer 1 Thickness (in) 1
Layer 2 Material PillowSoft Aire
Layer 2 Thickness (in) 1
Layer 3 Material Cool Twist Gel Foam
Layer 3 Thickness (in) 0.5
Layer 4 Material PerfectConform Graphite Memory Foam
Layer 4 Thickness (in) 1
Layer 5 Material Serta Support Foam
Layer 5 Thickness (in) 1
Layer 6 Material 5 ZoneActive Hybrid Design
Layer 6 Thickness (in) 8
Layer 7 Material Support Foam
Layer 7 Thickness (in) 1
Base Layer Material 5 ZoneActive Coil Unit
Product Depth (in) 79.5
Product Height (in) 13.5
Product Width (in) 76
Shipping Depth (in) 80
Shipping Height (in) 14
Shipping Width (in) 76.5
Product Weight (lb) 121.11
Shipping Weight (lb) 75
Adjustable Base Compatible? Yes
Antimicrobial? Yes
Breathable Construction? Yes
Coil Count 960
Coil Density 1211
Coil Type Pocketed Coil
Coil Gauge 0.068"/0.074"
Cooling Technology? Phase change material
Edge Support? Yes
Foam Infusion? Graphite
Handles Included? Yes
Is Mattress 2 Sided? No
Latex Free? Yes
Mattress Comfort Level Firm
Mattress Cover Design Floral
Mattress Cover Stitch Design Floral
Mattress In A Box? No
Moisture-Wicking? Yes
Pillow Top? No
Product Accent Color Light Blue
Product Cubes 52.1
Quilted Cover? Yes
Side Color Dark Blue
Top Cover Color Black
Zipper Cover Machine Washable? N/A
Zipper Cover? No
Product Warranty Length 10
Does it Ship in a box Yes

Quick Specs


  • Manufacturer

  • Brand: SERTA
  • Line: Perfect Sleeper X

  • Appearance

  • Type: Tight Top

  • Dimensions

  • Width: 13.5"
  • Height: 76"
  • Depth: 80"
Poster Image

Video Assets

Watch Video

Professional delivery and installation is available for every product we sell. We would be happy to coordinate delivery and installation for you.

Extended warranties are usually very inexpensive and can save you thousands in the future. It's simple and inexpensive to purchase extended warranties and one of the smartest ways to protect your investment.

Mattresses can be large, heavy and expensive. You probably don't have the special tools or expertise needed to fix them in a crisis. If you can spare a few thousand dollars without batting an eyelash for new bedding should they break tomorrow, don't buy a warranty. But if you're like most of us, protect yourself by purchasing inexpensive extended warranties when you buy a new product and save yourself big money in the long run.

4.6 out of 5

92% of reviewers recommend this product.

5 Stars

Best mattress ever!

Valerie M 10/31/2025

Comfy, supportive, firm edges. I returned a Casper mattress and got this Perfect Sleeper X. Back pain gone after first night and I sleep through the entire night now!
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Wonderful!!!!!!!!!!

Michael M 10/30/2025

No more sagging mattress, very supportive.
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Very Comfortable

Jeff L 10/17/2025

No more aches and pains when I wake up in the morning.
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Serta

Bertha S 10/13/2025

I like a firm mattress and this fits my needs
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Bed

Greg H 10/13/2025

Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Great mattress

Marsha M 10/11/2025

Comfortable, great night sleep
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Good product

Sheila T 10/5/2025

Comfortable and easy delivery… grateful.
Originally posted on www.serta.com

Yes, I recommend this product

4 Stars

So far so good!

Alin K 10/2/2025

I've only slept on my new mattress five nights and I really like it already.
Originally posted on www.serta.com

Yes, I recommend this product

4 Stars

So far so good!

Vincent W 9/30/2025

First week down. Mattress is very supportive.
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Sleep like a baby

Cindy D 9/22/2025

So firm! I love it!
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Excellent

Katherine H 9/21/2025

Supportive yet still feel I can sleep on my side comfortably!
Originally posted on www.serta.com

Yes, I recommend this product

1 Stars

bad product

Josif B 9/20/2025

Originally posted on www.serta.com

No, I do not recommend this product

5 Stars

Straight No Chaser, Comfort Sleep!!

Ronald W 9/18/2025

This mattress is, "da' bomb!" Folks, if you think I'm fibbin', get one! It seems to re-align sleeping posture, I miss work, on purpose to stay on this mattress! I removed the bedding to get model number for warranty- 10 years limited.
Originally posted on www.serta.com

Yes, I recommend this product

3 Stars

Firm but comfy

Betsy C 9/18/2025

It's a really nice mattress we just have to get use to the firmness!
Originally posted on www.serta.com

No, I do not recommend this product

5 Stars

Serta

Sheila G 9/18/2025

Mattress is very pretty in color and comfortable. I hope it will last at least 10 years.
Originally posted on www.serta.com

Yes, I recommend this product

4 Stars

Still in review only 2nd day

Irma G 9/18/2025

Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

John P like looks

John P 9/18/2025

Just got today, I'll know better tomorrow.
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Better than any mattress!

Angel B 9/11/2025

Bed is firm comfy…just the way we like it!
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Great

Won mee A 9/7/2025

Comfy and what we were looking for.
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Sleep deep

Wanda R 9/7/2025

Great night's sleep!
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Excellent and importantly so comfortable

Phyllis W 9/3/2025

Firm and comfortable
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

I bought your mattress because I liked it.

James G 9/2/2025

Firm and supportive!!
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Good quality

Sharron A 8/31/2025

Nice mattress good support
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

One good nights sleep !!!

Laura P 8/12/2025

Super nice mattress, nice and firm. I totally appreciate it. I made the right choice.
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Serta Knox Firm Mattress

Deborah F 8/7/2025

This mattress is very firm & comfortable mattress.
Originally posted on www.serta.com

Yes, I recommend this product

4 Stars

Owner

Viola B 8/3/2025

Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

hybrid Knox

Brendan G 8/3/2025

Originally posted on www.serta.com

Yes, I recommend this product

4 Stars

Serra for good rest

Cherrie K 7/31/2025

Comfy for back issues
Originally posted on www.serta.com

Yes, I recommend this product

4 Stars

Sister bed

Kendra S 7/17/2025

My sister seems to be comfortable and sleeps well through the night. No more saggy mattress she wakes up with a smile on her face.
Originally posted on www.serta.com

Yes, I recommend this product

4 Stars

New Serta Mattress

Edward V 7/16/2025

So far, comfortable and may help the back issues.
Originally posted on www.serta.com

Yes, I recommend this product

4 Stars

Love it

Crystal B 7/13/2025

I like firm beds. This is just what I needed. Comfortable.
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Love it

Carol L 7/11/2025

Once I lay down to sleep, I fall to sleep immediately and sleep the entire night. It is very comfortable and no aches or pains. I am totally happy and satisfied with it
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Best Sleep I've Ever Had

Cheryl M 7/4/2025

Very firm but comfortably supports my spine after two surgeries. I go right to sleep without tossing and turning like I did with my previous mattress.
Originally posted on www.serta.com

Yes, I recommend this product

4 Stars

Super firm

Shoi G 7/2/2025

I wanted a firm mattress and I found the perfect one.
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Great mattress - beautiful, well designed, and very comfortable

Eric T 6/26/2025

Love this mattress. Beautiful design and very comfortable. It has good support and a lovely cushioned top. Independent coil design with five comfort points is ingenious. We looked at every other brand, and this mattress was by far the best-designed and most competitively priced one we could find. Highly recommended.
Originally posted on www.serta.com

Yes, I recommend this product

4 Stars

Very firm and love the zero G

Laurie david K 6/25/2025

Very firm and love the zero G
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Perfect Sleep

Erica N 6/21/2025

Not too firm, not too soft, just right! In love with my new mattress. Highly recommend. It makes a difference!
Originally posted on www.serta.com

Yes, I recommend this product

3 Stars

Comfortable Sleep

James W 6/15/2025

Very firm. Looking forward to comfortable sleep.
Originally posted on www.serta.com

No, I do not recommend this product

5 Stars

Firm and comfortable

Denice S 6/15/2025

Supportive mattress!!
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Nice and firm mattress

Analuci M 6/13/2025

Looks really solid and durable. My son will love it!
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Good

Carolyn S 6/13/2025

Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Comfy

Debra B 6/10/2025

Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Comfy and firm

Ana carolina M 6/10/2025

Comfy and firm mattress
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Serta mattress

Richard S 6/9/2025

Very comfy mattress
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Perfect mattress

Benjamin M 6/4/2025

Comfortable, firm but not overly firm, and just right!
Originally posted on www.serta.com

Yes, I recommend this product

1 Stars

Missing stitches

Lamont E 6/4/2025

The mattress was delivered and had sitting missing on tp left side. Haven't heard back yet but for 2k they have to replace or repair.
Originally posted on www.serta.com

No, I do not recommend this product

5 Stars

Comfort and great price

Martin G 6/2/2025

We were shopping for comfort and price and we found this mattress. It fits in and the pricing as well.
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Excellent mattress

Mary T 5/28/2025

I love the Serta Knox firm mattress! Even though it is firm, it is comfortable and I can sleep without any issues.
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

Serta hybrid

Peggy B 5/27/2025

So comfortable. Sleep loke a baby. Love it
Originally posted on www.serta.com

Yes, I recommend this product

5 Stars

new mattress

Cynthia H 5/19/2025

Just delivered...much nicer than my 20 year old mattress
Originally posted on www.serta.com

Yes, I recommend this product