Giro: RELENTLESS PERFORMANCE AND STYLE The Syntax combines a touch of European flair with slightly deeper coverage and high-performance features - all tucked into a very slim design.The outer shell is molded from a tough polycarbonate that’s fused permanently to the EPS foam liner using our In-Mold construction process to enhance durability and ventilation without excess bulk.The fit is luxurious and secure, thanks to our highly adjustable Roc Loc 5 Air system that allows you to customize fit/feel for great stability and long-range comfort.  SPECS- Ionic+™ anti-microbial padding- Featherweight webbing with- Slimline™ BuckleCONSTRUCTION- Full-wrap In-Mold polycarbonate shell with EPS liner- Four polycarbonate hardbodiesFIT SYSTEM- Roc Loc® 5 Air MipsVENTILATION- 25 Wind Tunnel™ vents with internal channelingSUPER FIT™ SIZES- S 20”–21.75” / 51–55cm- M 21.75”–23.25” / 55–59cm- L 23.25”–24.75” / 59–63cm- XL 24”–25.55” / 61–65cmCERTIFICATION- Complies with the US CPSC Safety Standard for Bicycle Helmet for Persons Age 5 and Older