Rise up the ranks of the group ride and feel confident leading more turns in Trek's Circuit MIPS road helmet. Developed by brain surgeons and scientists, Multi-directional Impact Protection System (MIPS) technology helps reduce rotational forces on the brain caused by angled impacts to the head. Key features - Equipped with MIPS Brain Protection System - In-mold composite skeleton increases helmet integrity and larger vent variations - Intuitive, one-handed Headmaster fit system adjusts height and circumference - Soft, comfortable, moisture-wicking, and washable helmet pads - LockDown dividers make helmet strap management clean looking and easy to adjust - Internal, recessed channels manage airflow through the helmet and over the head - Design allows for compatibility and easy installation of Bontrager NeoVisor - Small = 51-57cm - Medium = 54-60cm - Large = 58-63cm