XINDA XDQ9650 Outdoor Speedway Expansion Cave Exploration Safety Helmet Climbing Equipment(White)1. Material: outer shell: ABS + PC; inner shell: EPS 2. Scope of use: rock climbing, mountaineering, expansion, cave exploration, fire rescue, rappelling head protection, etc 3. ABS material has high strength and good corrosion resistance 4. In the long term wearing of the helmet will produce internal heat, ventilation holes can effectively dissipate heat, breathable ventilation 5. When the adjusting device is rotated to the left, it can make the head