Beautyrest Black Hybrid KX-Class Firm Mattress Review

Updated October 28, 2022

Guy laying on his back on a Beautyrest Black Hybrid Mattress

The Beautyrest Black KX-Class Firm is a firm-feeling mattress made by Simmons and it comes highly recommended for its back support and pressure relief. This model is the medium comfort of the CX Class hybrid models in the Beautyrest Black collection.  We've reviewed this bed's features and benefits, please read on for our expert review:

Comfort Scale Rating

The CX Class Medium mattress is rated a 3 on our 10 point Comfort Scale (a 1 is hard, 10 is softest).  Most people will find a mattress with this level of comfort very appealing.  However, if you feel that your comfort preference is a bed that is either much firmer or very soft then you may want to consider the other KX Class model (plush) with a different comfort level. 

Expert Video Review

Here’s our quick CX-Class firm Mattress Video Review. It highlights the features, benefits, and our impression. 


Pros & Cons

  • Provides strong firm support
  • Hybrid construction is a very popular mattress construction style
  • Highly recommended for back sleepers 
  • Several layers of premium Memory Foams 
  • T3 Pocketed Coil System, exclusive to Beautyrest Black 
  • Comfort might not appeal if you prefer a very soft feeling bed 
  • Memory foams can smell odd for a short while before it dissipates completely
  • No Twin Size 

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Pressure Test Results

The Hybrid KX-Class Firm mattress was tested with petite, average, and large body size people on their side and back sleeping positions to see what kind of support and comfort you can expect. (Learn how we test.) 

Our pressure test results show that this mattress is recommended for back sleepers of all body sizes and petite side sleepers.  The only 'not recommended' score that this bed earned was for the larger-sized body side sleeper which is due to the increase of excess pressure on the peak pressure points, the shoulder, and the hip.  If you consider the images below, the bright red areas that are highlighted in the larger side sleeper exhibit where there's too much pressure on that particular joint. 

The yellow areas in these images indicate where there's a rise in pressure above what is considered normal, or acceptable.  What you really want to see are vast areas of green and light blue which means that the body is getting the exact amount of back support and pressure relief necessary for a good night's sleep

Your body needs proper back support for correct spinal alignment.  Without correct alignment, you'll likely experience head and neck pain, lower back discomfort, stiffness, and extreme weariness the next day all due to low-quality sleep from improper spinal alignment. 

Pressure relief in your mattress is just as important because excess pressure on your hips and shoulders can cause numb limbs which makes you roll around in bed to find a more comfortable position.  This then disrupts your sleep and makes for a pretty miserable sleep experience.  The KX-Class Firm tested fairly well for proper back support and good pressure relief, particularly for back sleepers. 

The pressure test results for this mattress are not yet available but it will be available soon.  Below is just an example.

LARGE PEOPLELargest 10% of adults 210-273 lbs Large back sleeper heatmapAvg Pressure:   mmHg - Area:   inches2 Large side sleeper heatmapAvg Pressure:   mmHg - Area:   inches2
AVERAGE PEOPLEMiddle 50% of adults 134-218 lbs Average back sleeper heatmapAvg Pressure:   mmHg - Area:   inches2 Average side sleeper heatmapAvg Pressure:   mmHg - Area:   inches2
PETITE PEOPLESmallest 10% of adults 111-135 lbs Petite back sleeper heatmapAvg Pressure:   mmHg - Area:   inches2 Petite side sleeper heatmapAvg Pressure:   mmHg - Area:   inches2

The Main Beautyrest Black Hybrid KX-Class Firm Features in Detail

KX Class Firm features

1. Antimicrobial Mattress Protection

Keeps mattress fresh and clean from odor causing bacteria.

2. BlackICE 4.0 with Plant-Based Cooling Technology

Cooling materials just beneath the surface enhance heat dissipation that help provide up to 18% more cooling power to keep you comfortable while you sleep.

3. AirCool Memory Foam 

This proprietary memory foam conforms to your body, provides pressure point relief, and freedom of movement.

4. Ultra HD Memory Foam

This High Density Memory Foam provides enhanced durability, pressure point relief and helps with motion separation.

5. Alpaca, Cashmere and Silk Comfort Layer

This layer is 100% natural and will help wick away moisture and enhance the cooling features within the mattress.

6. HD Memory Foam

Experience the perfect combination of comfort and support with HD memory foam. This high density memory foam conforms and contours to your body for personalized support.

7. Self Response Latex

Arguably the best comfort foam in mattresses, latex provides superior pressure relief for less tossing and turning while pushing back against the body for a more supportive feel. Anti-microbial and anti-dustmite properties contribute to a healthier sleep environment.

8. 2K Nano Coil

2000 micro coils provide enhanced conformability and pressure relief with individualized back support for each unique person.

9. T3 Pocketed Coil Technology

Exclusive to Beautyrest Black, this coil works to provide individualized back support, ease of movement, and pressure point relief throughout the night.

10. Energy Foam

This durable foam utilized below the coil unit helps create a supportive, durable foundation for the no-flip mattress design.


The Beautyrest Black KX-Class Firm mattress has a 10-year warranty against factory defects.

Beautyrest Black X-Class FAQs

  1. Do I need to flip my Beautyrest Black X-Class mattress?

    No, Beautyrest Black X-Class beds are built from the ground up and are not designed to be flipped. This has become the new standard for mattresses today. It often means more comfort materials can be packed in.

  2. How is this X-Class mattress constructed?

    The Hybrid X-Class Collection has a traditional innerspring, the Zoned T3 Pocketed Coil, combined with multiple layers of memory foams which is what makes these beds a hybrid.

  3. Can I finance my Beautyrest Black X-Class mattress?

    Yes! You can finance a Beautyrest Black X-Class mattress on US-Mattress with Synchrony HOME, Affirm, or Paypal.


The Black Hybrid KX Class Firm mattress is a firm-feeling bed by Simmons.  This comfort is popular because it makes a great compromise for couples who have different sleep preferences.  There is another comfort level in the KX-Class models if you feel that something plush might be your preference though.  

One of these mattresses' main features is the SurfaceTouch Gel Memory Foam infused into the mattress which helps air movement while being very soft and durable.  BlackICE Hybrid Technology is another feature that gives you a cooling sensation that also works to keep you cooler at night.  The multiple layers of foam combined with the T3 Pocketed Coil Technology create comfort and conforming support.  Our pressure testing has confirmed that this mattress performs particularly well for back sleepers with its excellent back support for proper spine alignment.  

This bed features the cheaper price of the KX Class models. This model is a great choice for a Beautyrest Black model, so long as you're willing to pay for premium quality.  I recommend this bed to anyone looking for a premium quality mattress, particularly if you're a back sleeper.

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Beautyrest Black KX-Class Medium Specifications:

Product Name
Beautyrest Black Hybrid KX-Class Firm Mattress
Mattress Comfort
Comfort Scale Number
Coil Count
Coil Gauge
Comfort Padding Layers
  • 10 Year Manufacturer Warranty Included

Back Support System
Quilt Top of Mattress
Edge Support
Recommended For Side Sleepers Who Weigh
  • Coming Soon!

Recommended For Back Sleepers Who Weigh
  • Coming Soon!

About the Author Steven Bieber

Features Steven, a white man with glasses, smiling

Steven is a content writer who recently broke into the mattress industry. In his free time, he enjoys watching football and listening to music.