Shoei Marquez4 X-14 Sports Bike Racing Motorcycle Helmet - TC-1/Medium Aerodynamic properties are maximized through extensive wind tunnel testing and professional riders' feedback Dual-Layer Multi-Density EPS liner enhances impact absorption and ventilation Four shell and five EPS liner sizes present increased fit options that help to comfortably fit most head sizes Impact absorbing EPS liner throughout the entire chin bar with Cheek Pad Cooling System Standard Rear Flaps can be replaced with optional, narrower flaps to customize aerodynamics, depending