Fits most adults (57~63cm Head Circumference) adjustable helmetMaterial:EPS+PC Size:57-63cm HeadHead wide 18 cm Head long 22 cm Wind tunnel: 18Weight: about 200gLightweight integrally-molded bicycle helmet.Made of EPS, high density, durable and comfortable.18 vents bring cool air in and flush warm air out, well-ventilated.With removable, , sweat absorption lining pad, comfortable to wear and easy to wash.Adjustable strap as well as adjuster within to adjust the size of head circumference.Stay safe while cycling with the bike helmet.Its compact style combined with the Advanced In-Mold polycarbonate shellShock absorbing inner for addedIt has 18 vents to reduce air resistance, keep you cool , comfortable, breathableFully Adjustable Straps and High Quality BucklePerfect for riding downtown, up a technical climb, and everything in betweenSpecifications:Lightweight integrally-molded bicycle helmetDurable and comfortable18 vents bring cool air in and flush warm air outComfortable to wear and easy to washAdjustable strapPackage Included:1 x HelmetNotes:Due to the difference between different monitors, the pictures may not reflect the actual color of the item.Compare the detail sizes with yours, please allow 1-3cm error, due to manual measurement.Please leaving a message before you give bad feedback if the products have some problems.Thanks for your understandings.