A cushion or mattress comprising an envelope 12 with laminated inner 14 and outer 16 layers and a resilient core 17 formed from open cell foam with upper and lower layers made of viscoelastic form and a central layer of resilient foam wherein the envelope is impermeable to air and liquid, the inner layer is attached to an upper layer of the core and a plurality of micro channels are formed on the top of the envelope. The envelope 12 can form a sealed chamber which is filled by the core 17. A bore may be provided in the core to allow air flow. A removable cover to provide vapour diffusion may be provided. The envelope 12 may have carrying means such as a strap, harness or handle. The device is designed to reduce the incidence of pressure sores and to make it easier to clean.
