Bontrager Rally Wavecel Mountain Bike Helmet Small. Olive Green / Orange. 20 - 23 ". 360g 12 oz. Unisex. Bontrager Rally WaveCel Mountain Bike Helmet Features: Rotational motion can cause brain injuries; with WaveCel, a collapsible cellular structure reduces rotational motion to the brain during impact Awarded 5 stars by Virginia Tech, a fully independent helmet-testing facility working to identify which helmets best reduce concussion risk Extended back-of-helmet shell offers additional rear protection BOA® Fit System lets you easily secure and adjust your helmet fit with one hand Soft, comfortable and moisture-wicking helmet pads are washable LockDown dividers make helmet strap management clean and easy to adjust Adjustable visor offers multiple coverage options Complies with U.S. Safety Standard for bicycle helmets for persons age 5 and older Crash Replacement Guarantee provides a free helmet replacement if involved in a crash within the first year of ownership Imported. To find your size, position a tape measure just above your ears and about 1 in. above your eyebrows. Keep the tape level to measure the circumference around the largest part of your head and then find the corresponding size in the Technical specs info. Technical Specifications Best Use: Mountain Biking Helmet Style: Mountain Bike Helmet Construction: Hybrid Shell Material: Polycarbonate Head Circumference: S: 20-22.4 inches Vents: 13 Visor/Brim: Yes Weight: S: 12.6 ounces Gender: Unisex