Powered mattress overlays are devices placed directly over a standard mattress. They utilize low air loss, powered flotation without air loss, or alternating pressure. An air pump or blower provides either sequential inflation and deflation or low interface pressure throughout. The inflated cell height measures 3 1/2 inches or greater, and surface design reduces friction and shear. Indicated for patients with limited mobility, major risk factors, or any stage pressure injury. These devices require electricity for proper functioning.