Troy Lee Designs A2 MIPS Bike Helmet - Silver Green/Grey The innovative A2 MIPS is Troy Lee Designs' MTB trail helmet that ticks all the boxes. The sleek helmet shell not only features large inlet and outlet ports, but also the best impact protection. From the retractable visor screws, to the innovative MIPS system and the industry-leading Dual Density EPP + EPS liner that protects against high and low speed impacts, the A2 is a helmet that doesn't take your safety lightly. Add in a revised adjustable strap and the X-Static Pure Silver helmet pad, and comfort equals protection in every sense of the word.