High quality - headguard are made of nylon and spandex. Sung Pads - this kind of helment is lightweight and covered with thicker pads which can protect your kid's head during doing exercise to avoid injury and exercise for a period of time does not increase the burden on the head. Breathable - Adjustable rear laces insure proper fit;The venting holes on the top ensure that you don't feel stuffy and the longer cheek length gives the maximum allowed protection to the upper jaw and cheekbone. Design - triangles and polygons pads high-performance EVA foam give the head a stable support and all-round protection from impact and abrasion. Size Chart - Adjustable chin strap and rear laces insure proper fit. The size:YS= 19 - 21inches (43- 48 cm), suitable for aged 3-5,YM= 21 - 23 inches (48-53cm),suitable for aged 6-11. Please refer to the size chart carefully before you place an order. If you are not sure, please to contact us and we will give you a reference.