The SM-8 helmet is filled with new technology such as Alpinestars patented visor system that has been developed to provide the right level of resistance to release when needed from impacts in any direction. The interior of the SM-8 helmet has been designed with maximum ventilation in mind. An interior air network channels incoming air through the helmet to keep rider's head cool, while continuing to pull hot air away and through the large exhaust vents. The helmet has been designed for riders that wear neck braces and those that don't. The bottom area of the helmet is raised to clear rider's collarbone area as much as possible. This gives dirt bike riders confidence while riding on the track, trail, or anywhere else. The SM-8 is also hydration system ready, as it has a channel inside the chin bar specifically for hydration tubes. Collarbone: The bottom side of the helmet is raised to clear the collarbone as much as possible for riders who choose not to wear a neck brace system. In addition, the bottom trim is soft on the collarbone area. The Alpinestars SM-8 is your ultimate motocross helmet, with the latest generation of MIPS technology, E-Ject prepared and multiple emergency release handles, Alpinestars has you covered! Lightweight outer shell is constructed from technologically advanced carbon in four sizes for best fitting ECE 22/05 certifications Multiple density inner liner Fitter with E-2, latest generation of MIPS, integrated low-friction layer designed to reduce rotational motion transferred to the brain from angled impacts to the head Visor attached to helmet shell with patented system that will allow easy release in case of crash Adjustable top pad height (Alpinestars patented A-Head system) Maximized ventilation with 19 intakes and 5 exhaust ports Side shell shape couple with soft EPP foam prevents damage to collarbone Emergency release and removable cheek pads, 3D contoured foam Removable comfort liner, anti-moisture and anti-bacterial fabrics Hydration prepared E-Ject prepared SIZE CHART XS = 53-54cm S = 55-56cm M = 57-58cm L = 59-60cm XL = 61-62cm 2XL = 63-64cm