The EPS resin in used for the molding of EPS products. It is manufactured in the form of very small polystyrene beads with a weight – average molecular weight between 160,000 and 260,000 and contains 4 to 7% blowing agent, usually pentanes or butane.The bead diameter can vary between 0.007 – inches (0.2mm) to 0.11 – inches (3.0 mm).