Memory Foam Mattresses have a technology produced by the use of polyurethane with additional chemicals which increase its viscosity and density. Memory Foam is often referred to as visco-elastic polyurethane foam. In some formulations, Memory Foam is firmer when cooler. Higher density Memory Foam Mattresses reacts to body heat, allowing it to mould to a warm human body in a few minutes. A lower density Memory Foam Mattress is pressure-sensitive and moulds quickly to the shape of the body. Here at Bed SOS we supply a vast range of Memory Foam Mattresses. We offer Next Day Delivery on all our Memory Foam Mattresses (UK Mainland only).