The M1 provides full-face protection and long-lasting comfort thanks to its foam padded internal muzzle providing maximum protection, cushioning you from abrasions and impacts. To keep you ventilated the helmet comes with 17 vents that are spread across the entirety of the helmets structure. Each vent is covered in meshing which prevents debris from entering the interior of the helmet. The wide face opening makes it easy to fit any goggles and the adjustable peak is held in place with two aluminium screws and a central thumb screw. Size guide: X-Small: 20.75" - 21.25" (53 - 54cm) Small: 21.5" - 22" (55 - 56cm) Medium: 22.5" - 22.75" (57 - 58cm) Large: 23.5" - 23.75" (59 - 60cm) X-Large: 24" - 24.25" (61 - 62cm)