This race inspired design is known for its great fit and great value with similar features to the s works prevail like the tri fix webbing system and 4th dimension cooling the propero ii handles even the most intense efforts on the pavement complies with one or more of the following safety standards for bicycle helmets cpsc snell b90a ce and asnzs 4th dimension cooling system with mouthport headset sl fit system with 4 position height adjustability is secure and easy to adjust on the fly w