AVAILABLE SIZES: For a perfect fit, measure the circumference of the head starting in the middle of your forehead to ensure you choose the correct size. S- fits 50-54cm; M- fits 55-57cm; L-fits 58-61cm IMPACT RESISTANT: This kids skate helmet features shock-absorbing and impact resistant. Material use tough and durable ABS and EPS foam which help absorb the impact and protect the head during impact. Helmet got CE Certification, it's a great safety guards for outdoor sports like skating and cycling. AWESOME VENTILATION SYSTEM: As designed with 11 multiple air vents, special aerodynamic design and breathable foam, the skate helmets help reduce sweating and keep cool even during intense body movement, which is considered as cool helmets for skateboarding or roller skate ADJUSTABLE: This sport protective helmet have two multiple adjustable straps and buckles for secure and size adjustment, could be flexible to different sizes for children. It can be adjusted to the growing child. FOR MULTI-SPORTS: As an ideal skateboard accessory, this skate helmet can also be used in many outdoor activities, such as roller skating, inline skate, scooter, cycling, rollerblading, long board and two wheel electronic board.