Vented High-Density Polyethylene (HDPE) shell designed with five raised channels running across the top for strength, and an extended back area for extra protection|EPS (Expanded Polystyrene) liner helps absorb impact|Unique "3D Adjustment" provides a precise fit using harness depth settings unlike any other hard hat on the US market today|Revolution™ Wheel Ratchet is easy to use and creates a firm comfortable fit|Includes a 4-point cross-over chin strap with quick release buckle that is adjustable for a safe & secure fit|Chamlon sweatband|Meets ANSI/ISEA Z89.1, Type I requirements, Class C requirements|Added impact benefits as outlined in the EN 12492 - Mountaineering Standard|Packed ready-to-wear with no installation of the suspension required|Universal accessory slots accepts virtually any helmet|EVOSpec™ compatible