Cannondale Dynam Road Helmet Cool, comfortable, capable The Cannondale Dynam is more than your standard road helmet. This helmet blends together ventilation, minimal weight, and a high level of protection-all in a helmet that functions just as well in a competitive road race, as it does exploring rural pavement on all-day adventures. At the heart of the Dynam is an inner foam core, that's bonded with the polycarbonate outer shell using an in-molded Smart Construction design, resulting in a lighter, stronger helmet. The Poly Rail system helps to reinforce the helmet's structure, designed to optimize airflow and even reduce weight without compromising integrity. The Dynam also features the MIPS Air Node protection system, the lightest version of MIPS currently available, reducing rotational forces during certain impacts without excess weight. Features MIPS Air Node protection system is the lightest MIPS system currently available, for rotational impact force reduction without the weight penalty Intelli Vent cooling directs a massive amount of airflow over the head for improved cooling efficiency Ergo Fit+ fit system with a rubber-molded dial for easy, precision adjustment Smart Construction is an in-mold system that bonds the inner foam core with the outer polycarbonate shell for increased strength Poly Rail system offers increased helmet rigidity and optimizes airflow Frame Lock Gripper for a secure hold of your glasses when stowed on the helmet Bio Map fit offers a better fit for more head shapes SPECIFICATIONSFit system Ergo Fit+ rubber moulded dial Closure system Fidlock magnetic buckle Intended Use Road, Gravel Weight320 grams (size M)Size Small Medium Large Head Circumference (cm)51cm - 55cm55cm - 59cm59cm - 63cm | Cannondale | Dynam Adult Helmet Men's | Size Medium In White | Rubber