With exceptional cooling & comfort features certified protection road-worthy styling & our exclusive Hair Port SX fit system thats tailor-made for a ponytail the Duet confirms itself as a tremendous value for any female cyclist. One-size system based on women’s head sizing designed for easy & accurate fit. 50-58cm fitment range Ponytail-ready Hair Port SX fit system with micro-adjustable dial for an easy accurate fit. 4th Dimension Cooling System optimizes ventilation. In-moulded shell improves strength & reduces weight. Tri-Fix web splitter for enhanced comfort & ease of strap adjustments. Reflective webbing & decals for increased visibility in low-light conditions. Patented clip-on visor included. Complies with one or more of the following safety standards for bicycle helmets: CPSC SNELL B90A CE & AS/NZS.