Giro Revel Bicycle Helmet. The Giro Revel Bicycle Helmet's confident style and superior ventilation combine with a compact design that complements any ride for any rider. Top level features like In Mold construction coupled with the ease and comfort of the Acu Dial fit system mean it's equipped to ride it all, from downtown streets to twisting climbs to singletrack trails. Its 22 vents serve up a massive amount of ventilation and a snap fit visor offers relief for your eyes in bright sunshine plus easily detaches when it's not required. Hands down, this is the best performance value in its class.