PETZL - Sirocco Ultralight Helmet Monobloc construction minimizes helmet weight while retaining excellent impact resistance, due to the mechanical properties of expanded polypropylene (EPP). Textile adjustment system also contributes to its lightness. Features a new magnetic buckle which allows the chinstrap to be attached with one hand. Has excellent ventilation distributed around the helmet. Materials: shell made of expanded polypropylene (EPP), straps made of polyester