bicycle helmet,Extremely light, stable and resistant to high temperatures thanks to the modern Inmold structure.The outer shell is made of hard polycarbonate and the inner is made of highly absorbent Styrofoam.Perfect fit thanks to the easy-to-operate one-hand size adjustment system using a smooth rotating regulator,With insect protection in both front openings,10 air channels for optimal air circulation,Extremely hygienic thanks to the removable and washable inner lining.Chin padding provides high wearing comfort.Reflective elements,Small/Medium: 51-56cm