Alternating Pressure Overlays are commonly used to reduce painful pressure points offering pressure relief therapy. These air mattress overlays are used by patients when they leave a hospital or physical therapy center. These alternating pressure overlays work with an existing twin size bed or standard medical bed frame. Alternating pressure overlays are available in variable adjustable and fixed models. These pressure relief overlays are often used by patients confined to bed, hospital outpatients, pregnant women for pressure relief when sleeping, patients in physical therapy, patients needing addition pressure relief for pain, bed sore healing or prevention. Free Fast Shipping !