Silas is your classic bike helmet revamped, refreshed, and ready for adventure whenever you are. Find your perfect fit with Silas' adjustable straps and ErgoKnob dial, and with 24 vents to feel the wind in your hair, you'll forget you're even wearing it. Features: Bike helmet designed for road biking 24 air vents and a contoured design for optimal airflow Interior padding wicks away sweat Interior padding is removable and easy to wash Easy-to-adjust nylon straps and an ErgoKnob dial for a snug fit Built-in 4-LED 3-function flashing safety light keeps you visible Complies with U.S. CPSC Safety Standard for Bicycle Helmets for Person Age 12 and older One Size: 21.25-24 in.