Giro Foray MIPS Helmet Matte Black/White, S Features - Streamlined Design, Plush interior, MIPS equipped Construction - In-mold polycarbonate shell with EPS Liner Fit System - Roc Loc 5 Ventilation - 21 Vents Sizing information: Small (51-55 cm / 20-21.75"), Medium (55-59 cm / 21.75-23.25"), Large (59-63 cm / 23.25-24.75")