Thank you for viewing! I purchased this for my child, but they only wore it once and didn't use it again, so I'm selling it. This product is CE mark approved, ensuring safety and peace of mind. Target age: 3-12 years old Head circumference: 50-57cm Helmet inner dimensions: (approx.) 19.5cm (length) x 15cm (width) Weight: approx. 205g Materials: Outer PVC, Inner EPS (Styrofoam) It's super lightweight and doesn't cause fatigue. The chin strap length is adjustable, and it's easy to put on and take off with one touch. It has ventilation holes for good breathability, making long rides comfortable.