Petzl Pro Alveo Best Professional Helmet PROTECT YOUR HEAD: Its closed shell offers protection against electrical hazards and molten metal spray. Impacts are absorbed by deformation of the expanded polystyrene liner. STAYS PUT: Strong chin strap (more than 50 daN) limits the risk of losing the helmet during a fall. LIGHTWEIGHT: Built for reduced weight, the ALVEO BEST only weighs 350 grams. COMFORT IS KEY: CenterFit adjustment system adjusts the headband and keeps the helmet centered on the head. PERFECT FIT: The ALVEO BEST comes with two sizes of headband foam.