Size Chart : S: 20.9 – 21.3 inch M: 21.7 – 22.0 inch L: 22.4 – 22.8 inch XL: 23.2 – 23.6 inch; Advance Aerodynamics Design Quick Release Buckle Design; Ultra light weight durable aerodynamic thermoplastic alloy shell; Heavily cushioned and comfortable interior Removable and washable; Beautiful glossy UV protective finish; DOT Approved
- S 53-54 CM20.9/21.3 Inch.
- M 55-56 CM21.7/22.0 Inch.
- L 57-58 CM22.4/22.8 Inch.
- XL 59-60 CM23.2/23.6 Inch.