Special featuresBOLT system - ensures compatibility between a large number of accessories with a simple and intuitive attachment system.Extremely comfortable and easy to adjust with the wheel ratchet.Shell made of ABS for light weight.6-point suspension for greater comfort.Replaceable and comfortable sweatband.Size: 52 - 68 cm.Available in 8 colors with a glossy finish: white, yellow, orange, red, black, green, blue, and high-visibility yellow.Certified according to EN 397:2012 with optional requirements for multi-metal, extreme temperatures -30°C, lateral deformation, and electrical insulation 440 V a.c. (electrical insulation 440 V under EN397 only on the version without venting).Certified according to EN 50365:2002 Electrical Class 0 for installations with a nominal voltage up to 1000 V a.c. and 1500 V d.c. in vented and unvented versions.