1. AdjustableSize The size of the helmet is 58-61cm and has an adjustable range of 3-4 cm. Adjust the size of the helmet to the different rider's head circumferences by turning the knob 2. The Well-thought-out Design of the SideStraps Quick Release Buckle-easy to put on and take off thehelmet Adjustable Side Straps Length -can better fit the helmet to your head for the most comfortable wearing Chinstrap with Soft Padding -effectively prevents damage to the chin skin caused by repeated friction between the side straps and the chin 3. EPS foam InsectNet The inner shell is made of high-density EPS foam, which has a light texture, strong shock absorption, is durable, and can effectively cushion an impact to the head in the event of an impact The helmet is equipped with an insect net that prevents mosquito bites on the head very well during the forward process 4. 15 VentilationHoles The adjustable bicycle helmet has 15 vents to increase air circulation, effectively reducing sweat and keeping your head comfortable and cool while riding