Abstract: A body support device having a gas inlet to receive a supply of pressurized air and having a plurality of gas outlets in fluid communication with the gas inlet. The outlets are orifices at the upper surface of the support device. The support device may be an inflatable mattress, cushion or the like. A plurality of valves are attached to the support device at the orifices and are biased into positions to obstruct gas flow through the orifices. Vertically displaceable members extend to a level with respect to the upper wall of the support device such that a force applied to the upper wall about a member urges the member downward. The vertically displaceable members are mutually independent, but each one is in motion-transfer engagement with one of the valves to independently move the valve into a gas-release position upon downward movement of the displaceable member. In a preferred embodiment, the displaceable members are hammers having downwardly extending projections in contact with the associated valve.