Alternating Pressure Relief Bubble Pad System.  Designed for patients who are unable to reposition themselves frequently or are at risk for skin breakdown and friction burns.  2.5” alternating pressure relief system specifically designed for the treatment of pressure sores stage l and II, and for prevention. Control knob adjusts comfort range in 8 levels. Pressure range 30-80, cycle time 8 min/60Hz, 9.6 min/50Hz. Features patented air compressor chamber with ultra-quiet operation, external air filter intake, and securing straps on the mattress. Weight capacity: 220lbs.