OutdoorMaster Skateboard Cycling Helmet - Two Removable Liners Ventilation Multi-Sport Scooter Roller Skate Inline Skating for Kids, Youth & Adults Durable: Built for both comfort and impact resistance with reinforced ABS shell & thickened shock-absorbing EPS core Extra Removable Lining: Skateboard helmet with two removable liner for different head sizes and easy to wash the sweat away A Helmet for Multi-Sport: Smooth Ventilation System helps to protect and enjoy skating, cycling, BMX, MTB and etc Double Adjustment: Well-attached & long-lasting adjustment dial and skin-friendly adjustable chin strap maximize the best fit and comfortable wearing How to Measure A Proper Helmet: To find the right size bike helmet, start by measuring your head circumference, wrap a flexible tape measure around the largest portion of your head about one inch above your eyebrows. Or, wrap a string around your head, then measure the length of string with a yardstick. Size Large is recommended if your size is between 21.3-22.8 inch (54 cm-58 cm). The recommended Age Grading: 5 Years and Older