King Koil Xtended Life Onyx Extra Firm

Purposeful materials, craftsmanship and quality for more of what you want and need to sleep well. Having a good night’s sleep every night starts with the right details. The King Koil Xtended Life Onyx Extra Firm mattress gives you more of what makes sleep good. Our most trusted mattress consistently delivers long-lasting daydream worthy sleep by making every thread, coil and inch of foam count.

Extra Firm Mattress-Layered with a Silk Wool Blend, Graphite Talalay Latex and a Contour Pro Encased Coil System to give you the perfect support you need.
King Koil Xtended Life mattresses are for people who are ready to invest into a better quality of sleep.

PureCare Silver five Sided Mattress Protector

from $110.00

get it Delivery date contingent on available inventory

Healthy Sleep Ultra-Tech Advanced Pillow

from $99.00

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Multiple Colors

DreamFit Pima Cotton Sheets

from $129.99

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Add it

subtotal:

$2,399.99

get it Delivery date contingent on available inventory

Local
Delivery

Local delivery and set up is included for a flat fee of $69.99 within 25 miles of any Sit ‘n Sleep store.

We will also "haul away" your old mattress and box spring upon delivery of your new order: Just let us know!

Next day delivery on available inventory. Not applicable for UPS and FedEx orders. See our COVID-19 page for more information.

120-Night Sleep Trial

Buying a new mattress is not something you do everyday. Our 120-night sleep trial and comfort guarantee means you can rest easy.

10 Year Warranty

You spend a third of your life asleep on your mattress. Shouldn't you at least lay on it first? Come visit one of our 39 store locations and get comfy with your purchase.

Mattress Removal

We will "haul away" your old mattress and box spring upon delivery of your new order: Just let us know if you would like this service.

Add a Base and Frame:

Knickerbocker Promo Frame

from $67.00

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Primo Rapid Foundation

from $299.99

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Sealy Ease 4.0 Adjustable Base

from $899.00

get it Delivery date contingent on available inventory

Have Questions?

We're here to help. Give us a call or visit your local store.

Extra Firm

Extra Firm Mattress-Layered with a Silk Wool Blend, Graphite Talalay Latex and a Contour Pro Encased Coil System to give you the perfect support you need.

Key Feature

An everlasting design for a lifetime of sleep.

Ready for Your Best Night’s Sleep?

Proudly Designed, Handcrafted and built in the USA since 1898

Mattress is adjustable friendly - works well on motion bases.

Mattress Height (Approx.) 12”

25Year Warranty

SUPER STRETCH TENCEL FABRIC: Moisture wicking natural & breathable sustainable

SILK WOOL BLEND: Natural & breathable durable cooling comfort sustainable

2 LAYERS OF GRAPHITE TALALAY FIRM LATEX: Pressure relieving support highly resilient & durable wicks away moisture & heat

CONTOUR PRO ENCASED COIL SYSTEM: Reduces motion disturbance conforms to body’s curves relieves body pressure points

ADDITIONAL FEATURES: Anti-Microbial Safeguard Fibers, Super High Density Foam, High Performance Foam, HD Foam Encasement, Everlast® Base Foam

Approx. 

Twin 38" x 75" x 12" 

Twin XL 38" x 80" x 12" 

Full 54" x 75" x 12" 

Queen 60" x 80" x 12" 

King 76" x 80" x 12" 

CA King 72" x 84" x 12"

What Customers Are Saying