The Bell 4Forty MIPS helmet has 15 ventilation openings and is made from a Fusion In-Mold polycarbonate shell.Features:- Designed for MTB- Weight: 380 g- 15 openings- Complies with the U.S. CPSC safety standard- Fusion In-Mold Polycarbonate Shell- Fit system: Float Fit- Adjustable Google Guide visor system- Padding with anti-sweat guide- Flat belt clamping systemTechnology:- MIPS is the leading helmet slip plane technology, designed to reduce rotational impact of certain knocks. When the head rotates rapidly and comes to a sudden stop, the rotational acceleration can cause high levels of stress in the brain tissue. The tissue strain caused by these movements can result in various types of brain injuries. We believe that helmets equipped with MIPS technology can add the highest level of protection against certain types of impacts. MIPS uses a slip plane technology that moves inside the helmet, mimicking the same protection system that the brain uses.