M size Although it is new and unused, there is a scratch on the inner fabric. It's difficult to see in the photos, but please check the 14th photo. 【Security and Protection】The children's bicycle helmet uses a durable and sturdy PC shell and lightweight, shock-absorbing EPS foam, effectively absorbing the impact to the head during a collision and minimizing damage. The bicycle helmet for elementary school students has a thick and soft heat-sealed lining and chin pad, firmly protecting children's heads from friction and impact. 【Excellent Ventilation and Breathability】The children's bicycle helmet has 18 ventilation holes, and the inner lining is made of breathable material, providing a comfortable wearing experience. The aerodynamically designed, highly breathable design allows wind to pass through the helmet, increasing speed while keeping you cool. 【Lightweight and Adjustable】The bicycle helmet uses EPS foam with excellent shock absorption, allowing children to enjoy sports comfortably without feeling the weight. It is equipped with three adjustment systems: a removable sun visor, an adjustable head size wheel (easily adjustable with one hand), and an adjustable chin buckle. Even children can easily use it, providing solid protection while learning how to wear it safely. 【Perfect for the Target Age】The bicycle helmet is suitable for boys and girls. Adjustable sizes S (50-55CM) and M (54-59CM) fit perfectly as they grow. It is ideal not only as a bicycle helmet but also for elementary school students commuting to school. The bright and colorful, stylishly designed children's helmet combines safety and fashion. 【CE Safety Standard + 3-Month Warranty】The CE standard is a safety standard recognized as one of the standards for bicycle helmets distributed in EU member countries and worldwide. It has obtained safety standards and also offers a 3-month free return and refund support. If you have any problems with the product, please feel free to contact us.