The GRZ helps to reduce interface pressures by dynamically adjusting to body weight and movement. It is a non-powered pressure relieving mattress with nine individual dynamic self-adjusting air bladders inside a high resiliency foam shell. The nine zones relieve pressure where it is needed most. Supports patient weights up to 1000 lbs. with bariatric models.- Self Adjusting Air Pressure Wheelchair Cushion, 20 x 16" Mfr. Direct