High-Density Polyethylene (HDPE) shell designed for strength. 4-point suspension with 3-dimensional height adjustment. Wheel ratchet is easy to use and creates a firm comfortable fit. Premium moisture managing sweatband. Universal accessory slots accepts virtually any competitors' accessories. Meets ANSI/ISEA Z89.1,Class E / CSA Z94.1-05, Type 1 requirements. One size fits most.