The new Petzl Altios helmet features a hybrid suspension system, composed of a mesh panel and an expanded polystyrene liner, which makes this helmet extremely lightweight and comfortable to wear. Thanks to this innovative design, the helmet "levitates" above the head for a near-weightless feeling. The space between the head and the liner allows for effective ventilation with the Climate Control System. The outer shell is constructed of durable ABS. This helmet is very ergonomic, adapting to almost any head shape and offers two options for attaching a headlamp: a removable system-compatible mount, or clips. Features: Lightweight and comfortable fit, thanks to a hybrid suspension system combining an expanded polystyrene liner for shock absorption Comfortable mesh inner liner makes the helmet feel weightless when on the head Durable construction: ABS shell provides protection Climate Control System: provides ventilation between the inner shell and the top of the head (can be closed in cold weather with the 6 plugs stored in the inner shell) Removable ADAPT clip, for easy attachment of any Petzl headlamp equipped with the ADAPT system (TIKKA/ZIPKA family) Removable and washable headband foam and mesh Easy-to-use, molded adjustment wheel quickly dials in the headband size, even while the helmet is being worn Adjustable chinstrap, nape height and headband for an extremely comfortable fit Chinstrap can be adjusted forward or backward for added comfort. Adjustment buckles are placed to the side, away from the chin Narrow polyester webbing straps offer improved comfort Headlamp attachment with 4 optimally placed clips Compatible with VIZION face shield Specs: Size 1: 48 - 56 cm (18.9 - 22 in), 315 g (11.1 oz) Size 2: 56 - 61 cm (22 - 24 in), 345 g (12.2 oz) Colors: White, Platinum, Orange CE / UIAA Materials: ABS shell Expanded polystyrene foam liner Polyester webbing straps 3 Year Guarantee Made in China