The troy lee designs a1 mips mtb helmet features a triple position adjustable retention system which means you can customize the fit to be exactly right whatever your head shape or riding style whether you wear goggles or shades no matter how hard you push it 8 pressurized air intake passages and 8 rear vacuum vortex outlets along with the anti microbial moisture wicking liner will keep your head cool and fresh if you want a versitile off road helmet featuring a premium fit and su