The Alveo Best from Petzl is a lightweight helmet for work at height and rescue. This helmet features comfort foam and is barely felt on the head. Shock is absorbed by deformation of the expanded polystyrene liner. Specifications Head circumference: 53-63 cm Weight: 340 g Material(s): ABS, expanded polystyrene, nylon, polycarbonate, high-strength polyester, polyethylene. Contains Alveolen® of Sekisui Alveo AG Certification(s): CE EN 12492 *, ANSI Z89.1-2009 type I classe C, UIAA * Meets the requirements of the EN 397 and EN 12492 standards for impact protection