A3 Helmet W/MIPS So comfortable you won't ever want to take it off. The A3 mountain bike helmet is a new standard in premium mountain bike helmets with luxurious comfort, patent-pending innovations in safety, ventilation that will you keep you cool on the longest climbs with comfort and coverage to protect on the sketchiest of descents. Highest possible score (5-STAR) from Virginia Tech helmet safety lab so you can feel confident in all conditions.