The Uvex i-vo is a jack-of-all-trades. Thanks to its IAS-3D+-system, the i-vo adjusts to your head in length, width and height for a custom fit. One twist of the rear dial, and your helmet perfectly cradles your head with no hot spots. Multiple, big vents let a torrent of air in to keep your head nice and cool. Other well-thought-out details include a changeable inner liner, a ratcheting chin-strap buckle and mesh screening on the front vent to keep bugs out.