The troy lee designs a2 mips mtb helmet is the first helmet in its class to combine epp and eps to offer optimum protection for low speed and high speed impacts in one sleek stylish package an upgrade on the popular a1 helmet the a2 features improved ventilation with 25 larger air intakes and massive exhausts to keep your head cool and comfortable so you can concentrate on the trail ahead mips patented brain protection system mips multi directional impact protection system is a revolution