The troy lee a2 mips 5050 helmet the all new for 2017 a2 helmet redefines mountain bike safety style comfort and ventilation the first helmet in its class to combine epp for slow speed impacts and eps for high speed impacts in one sleek package that will set a new benchmark for mountain bike helmets troy lee a2 mips 5050 helmet features huge air intakes 25 larger than a1 connected to massive exhaust ports through deep internal channels provide powerful cooling