Bern Unlimited Brentwood Summer Helmet with Flip Visor ALL SEASON - Pick the model that best fits your style and customize your helmet with our range of seasonal upgrades. Winter Upgrade Kit Available Separately BIKE LIGHT COMPATIBLE - The Asteroid and Meteoroid fit all new and older Bern helmets with a two-hole mount located in the rear of the shell CRANK FIT - Tried and true proprietary dial adjustment system. Simple and durable STANDARDS - Meets Safety Certification CPSC, EN1078 SIZE CHART: S-M (54-57 cm), L/XL (57-60.5 cm), XXL/XXXL (60.5-63 cm)