Viscoelastic foam products consist of viscoelastic, 100% open cell foam that is temperature sensitive. The foam becomes softer at operating temperatures near body temperature. The effect of this softening is that the layer of foam nearest to the body provides improved pressure distribution through envelopment when compared to high resilient foam. The viscoelastic foam acts like a self-contouring surface because the elastic response diminishes over time, even after the foam is compressed. The disadvantage of the temperature and time sensitive response is that the desirable effects may not be realized when the ambient temperature is too low. The properties of viscoelastic foams vary widely and must be chosen according the specific needs of the patient for both seat and mattress applications.