Expanded polystyrene (EPS) is a rigid and tough, closed-cell foam. It is usually white and made of per-expanded polystyrene beads. EPS is used for disposable trays, plates, bowls and cups; and for carry-out food packaging (including the hinged lid containers popularly known as "clam shells"). Other uses include molded sheets for building insulation and packing material ("peanuts") for cushioning fragile items inside boxes. Sheets are commonly packaged as rigid panels which are also known as "bead-board".
EPS has been a material of choice for over half a century because of its technical versatility, performance and cost effectiveness. It is widely used in many everyday applications where its light weight, strength, durability, thermal insulation and shock absorption characteristics provide economic, high performance products.