A closed cell of foam plastic

Expanded Polystyrene (EPS) is a closed cell, lightweight, rigid foam plastic. Composed of carbon and hydrogen molecules, it is derived from petroleum and natural gas by-products. Molded EPS is non-toxic and no chlorofluorcarbons, usually referred to as CFCs, are used in the production.
EPS is environmentally friendly.  Due to its strength and excellent insulation value, less material is needed.  Less energy is used in the manufacturing compared to alternative materials. EPS does not support microbiological growth. EPS"s properties of low thermal conductivity, high compressive strength, and excellent shock absorption properties make it an ideal material for an insulating concrete forming system. EPS foam is also the material commonly found in protective cushion pads for computers, and other electronic equipment.