Features: brand new and high quality Adjustable for Head Circumference: The bicycle helmet has an adjustable design. There is an adjustment button on the back of the bike helmet that allows you to adjust your for head circumference.(for head circumference: 52~56cm). Aerodynamic Design, Breathable: The bicycle helmet adopts a special aerodynamic design with 13 large ventilation vents, which effectively reduces air resistance and sweating. Shock Absorption and Safety Guarantee: Rugged PC for shell and EPS foam absorb shock and impact. An innovative styling system combines the for shell with thick EPS foam to create a for stronger helmet that provides superior impact resistance to protect you on road and mountain biking, as well as everyday trails. Lightweight helmet and soft inner pad: This bike helmet weighs only 420g, which is very light. Specifications: Material:EPS+PC for Head Circumference:Approx. 52~56cm/20.47x22.05in Inside Size:Approx.17.5X20cm/6.89x7.87in Lining Material: Polyester Fiber Color: Black, Red, Yellow, Rose Red(Optional) Vents: 13 Vents Suitable Age: 5-10 years old Uses: Outdoor sports for protection such as bicycles, balance for cars, scooters, skating, etc. Package Includes: 1 x Helmet note: Please allow 1-2cm errors due to manual measurement,pls make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item.