Cannondale's Quick Junior helmet is a comfortable, light weight kids helmet. XS/S size fits 48-54cm, SM/M fits 52-57cm. In Fusion mold technology makes this helmet very durable and light-weight Easy Fit System with micro-dial and plush padding makes adjusting the helmet size effortless and precise Vent Screens stop bugs, not air flow Comfortable soft-touch webbing w/ pinch guard allows for quick connect and a comfortable ride