Case studies and experience has proven that alternating pressure surfaces are highly effective in the prevention and treatment of pressure wounds. These chairs provide the maximum amount of pressure relief possible in a seated position. These chairs both offer alternating air cells (Standard Air Chair has 38 and Air Chair 550 has 46) with 2H inflated cells and a two-minute cycle. The welded steel frame has a moisture-proof cover.Control Box for Air Chair Recliners sold separately