This form of helmet construction is an industry standard. Here a lightweight, polycarbonate shell is fused to an EPS foam liner for absorbing impacts. The fusing allows for various types of ventilation to be incorporated into the helmet design. EPS, or expanded polystyrene, is a form of closed-cell foam that is tough and very rigid. This combination results in a good all-around helmet that is light and cool while still maintaining a high level of protection for the wearer.