Giro Shiv Snow Helmet Fit Kit Sizes: S (52-55.5cm), M (55.5-59cm), L (59-62cm) Giro Fit Kit Pads system allows you to dial in your fit using different thickness comfort pads on the interior of the helmet. Just pull the hook and loop-backed pads out and swap them out for the thickness you need In-mold construction: tough polycarbonate outer shell combined with impact-absorbing foam liner. Interior Subliner: allows you to customize your pads or pull them out completely for the ultimate in rider tuned fit. 8 Super Cool Vents with Weatherstrip vent plugs: pull cool, fresh air into the helmet while pushing heat and stale air out. Help regulate your core temp. Compatible with all after-market TuneUp systems