SAFTY FOR ALL SITUATIONSSinging Rock's Penta Climbing Helmet is so ultralight that you'll barely notice, until rocks come pummeling down and you're still conscious. This helmet's hard PC shell prevents sharp objects from penetrating, while the PS foam absorbs impacts on falls. There are 11 large vents for comfortable airflow in summer conditions. There is also a flexible rear retention system with adjustable straps at the chin and back for a secure fit. FEATURESShell Material: polycarbonateImpact Foam: polystyreneVentilation: 11 passive ventsFit Adjustment: adjustable headband