# SLEEP100 Extra Firm King Mattress, 12-Inch Gel Memory Foam, Fiberglass-Free

SLEEP100 Extra Firm King Mattress with gel-infused memory foam helps create a stable, cooling-focused sleep surface for shared bedrooms.

- [Original product page](https://www.ofertitastop.com/us/product/sleep100-extra-firm-king-mattress-12)
- [View offer](https://www.ofertitastop.com/us/visit/sleep100-extra-firm-king-mattress-12)
- Market: US
- Language: en-US
- Currency: USD
- Product updated: 2026-10-17T06:43:47.086Z
- Brand: SLEEP100
- SKU: ofertitastop-us-135174
- Category: Furniture > Beds & Accessories > Mattresses
- Source store: amazon US
- Active deal: Yes
- Price: 314.98 USD
- Previous price: 359.99 USD
- Discount: 13%
- Rating: 4.7 / 5
- Reviews: 112

Prices and deal status are the latest recorded data, not a guarantee of availability. Confirm the price and availability with the store.

## Description

Some sleepers prefer a close, contouring feel, while others want a firmer surface with less sink. The SLEEP100 Extra Firm King Mattress is designed for the second preference, with a layered foam construction and a high-density support core. Gel-infused memory foam and a breathable knit cover add cooling-focused details for everyday rest. Its spring-free design also helps limit motion transfer across the bed.

## Tech summary
- Size: King
- Dimensions: 80" L x 76" W x 12" H
- Firmness: Extra firm
- Construction: Three layers of gel memory foam and memory foam
- Cover: Polyester
- Weight: 71.5 pounds
- Weight limit: 1,500 pounds
- Certifications and materials: CertiPUR-US certified foam, fiberglass-free, fabric tested to OEKO-TEX standards

The extra-firm feel is intended for sleepers who value a stable surface, and the support core is designed to help distribute body weight more evenly. That construction supports alignment through the back, hips, shoulders, and neck without relying on springs. The gel-infused foam and breathable knit cover are designed to encourage airflow and help reduce heat buildup, while the softly quilted top adds a comfortable surface layer.

## Requirements
The mattress works with most bed frames, including platform beds and adjustable bases. Its King dimensions are 80" L x 76" W x 12" H, so match the frame to that size for a proper fit. It arrives compressed in a box, allow 2–12 hours for it to expand before use. This setup makes delivery and placement easier to manage than moving a fully expanded mattress into the bedroom.

## Getting the most from it
For couples or light sleepers, the foam layers contour to the body and absorb movement at its source, helping reduce motion transfer across the surface. The spring-free build also creates a quiet sleep space. This can be useful when one person changes position while the other is resting, without claiming to eliminate every movement.

To make the most of the mattress’s feel, give it the stated expansion time after unpacking, then use it on a compatible frame. The extra-firm support and King size suit a shared sleep surface where room to stretch matters, while the cooling-focused foam and cover address comfort through the night. Its certified foam and fiberglass-free construction are additional material details for shoppers who consider certifications and mattress materials when choosing a bed.

## Should you buy it?
Choose this SLEEP100 mattress if an extra-firm feel, King sizing, and a spring-free foam design match how you want to sleep. Its support-focused layers, motion isolation, and gel-infused foam bring distinct practical benefits to a shared bedroom or a sleeper who prefers a more stable surface. The boxed delivery and compatibility with most frames make it a straightforward fit for setting up a new bed at home.

## Images

![SLEEP100 Extra Firm King Mattress, 12-Inch Gel Memory Foam, Fiberglass-Free — 1](https://www.ofertitastop.com/i/ekrM2sNcFFBk9XWhiDhZ-vq-90D90Y85u2ref73NSVO1Rt9QDRGJ-49JkXAJ7smcBcfn5Quh_WuV2rxdPA31pjJ7iHJa90rD8HCgxv9g3BG35-SMQNCNUQej8Q.jpg)

![SLEEP100 Extra Firm King Mattress, 12-Inch Gel Memory Foam, Fiberglass-Free — 2](https://www.ofertitastop.com/i/ymqkq9wLvOI6F3Ue9JzbE4T7FzrHTnDGATqikY8JWCs9HIWIbNffeaIJJm32T2gHQoUq0PCY0Zlcx5qh9a4qhvi3cWqhfAmKwO6D6D7A2mjeTXofJ_CF0_dfnQ.jpg)

![SLEEP100 Extra Firm King Mattress, 12-Inch Gel Memory Foam, Fiberglass-Free — 3](https://www.ofertitastop.com/i/kR71QPewn0MqEpLAnDzI_34SG1pu3_9b1p9MwxFyqvhunqpvxGoNc9ZvDMSelWHJwe5H-1M3fH4bR57tOOVIJ7i0ntZ5RHzPVS8apoiKkFonSmQmb7PmOnRzXg.jpg)

![SLEEP100 Extra Firm King Mattress, 12-Inch Gel Memory Foam, Fiberglass-Free — 4](https://www.ofertitastop.com/i/gicN4FYr6HoppW0ODudzmg4plkS_7dHWRL8gfaxlsl0Oh_uK_K6Ch3nVhco0ISigcyu5ujTVA_LEBv9zML_t3Rp8peTD9TGrhQROv2I3XVh9dslfsOp82v3wxg.jpg)

![SLEEP100 Extra Firm King Mattress, 12-Inch Gel Memory Foam, Fiberglass-Free — 5](https://www.ofertitastop.com/i/YJVBBTKpx2Hx9Mk8HmPOPS2M87QQHTNaRcXxAXBwPelwi5_us1PXnyhgkL0cSrR5avvDVz3OlpViKDex31pGjGP71MjvXdxVZvvnwo1c7PORgpqNGb3eHEtTyA.jpg)