The 80Six Dual Certified Kids' Bike, Hoverboard, and Skateboard Helmet offers unparalleled protection for boys and girls ages five and up. The classic shell shape, designed by leading action sports brand Triple Eight provides comfort and ventilation for hours of biking, skateboarding, rollerblading, longboard, and scooter fun. Featuring an ABS outer shell for durability and protection, and an EPS liner with inner foam pads that mold to the head for a comfortable fit, the helmet complies with U.S. CPSC Safety Standard for Bicycle Helmets for Persons Age 5 and Older and ASTM F-1492. Available in 3 sizes: Junior - Ages 5+ fits ages five and up, head size of 49-52cm (19.25-20.5in); Small/Medium - Ages 8+ fits ages eight and up, head size of 52-56cm (20.5-22in); Medium/Large - Ages 14+ fits ages fourteen and up, head size of 55-58cm (21.7-22.8in). An adjustable chin strap with side release buckle ensures a secure fit. For most accurate measurement, use a string to measure the circumference of the head. Designed in New York and made with care from the same team who brought you Triple 8 and 187 Killer Pads. Manufacturer's 180-day limited warranty.