This therapeutic support has 20, eight-inch horizontally configured bladders. The dual quilted cover with slip layer helps prevent friction and shear. The non-skid, 1000 Denier nylon bottom as well as 10 nylon web buckled hold downs secure mattress to bed. It delivers alternating pressure with a powerful 50 LPM compressor and will not bottom out as long as mattress hose stays connected to the compressor even in a power outage.