RESTORATIVE SLEEP: Engineered to create a neutral spine position that’s better for your back and posture — helping to reduce pressure on your circulatory system and compelling you to inhale more oxygen while you snooze. Our foams are thick and dense to give you firm support while soothing hips and shoulders for restorative sleep. The American Chiropractic Association (ACA) concluded that the mattress’s firm support reduces spinal stress, improves lumbar support, and alleviates back pain. CUSTOMIZABLE FIRMNESS: If your extra firm mattress feels too firm, simply flip the mattress to achieve a medium-firm feel. Flip for firm or firmest—the choice is yours. (Plus, the flippable design improves the longevity of the mattress.) Many customers with a sleep partner do opt for the Plank Firm Luxe to ensure a more comfortable sleep experience for both individuals. COOLING UPGRADE: Hot sleepers and sleep partners find relief with our optional GlacioTex cooling cover. This cool-to-the-touch design offers instant cooling to banish heat and restore long-lasting cool sleep. FIRMEST ALL FOAM MATTRESS: Never feel your back dip and never opt for the floor again. This 10 inch all foam mattress offers extra firm support (a ten on the firmness scale) and will keep you firmly supported all night long. Designed to support up to 950 lbs. CERTIFIED SAFE MATERIALS: This bed in a box mattress is Fiberglass-free, GREENGUARD Gold certified, and made with CertiPUR-US foams. Each mattress is carefully assembled in our own Arizona facility and delivered right to your door. We want you to be happy with your mattress and that's why we offer a 120 night sleep trial. This dual sided ultra firm mattress allows you to choose between the firmest sleep experience available, or a medium-firm sleep experience. The choice is yours with just a flip of your mattress. This sleep surface is inspired by the minimalist approach to sleep found in places like East Asia, while including a more modern mattress design. Enjoy relief from back pain with a sleep surface that helps you achieve a neutral spine while also aiding proper blood circulation and better oxygen intake. The firmest mattress available, guaranteed. (Available with an optional sewn-on cooling cover from high tech PE fibers.)