Polycarbonate Plastic Shell with EPS foam Helmet inside is lined with removable, high-performance pads for increased comfort and easy cleaning Adjusting knob at the back of the helmet, to adjust the head circumference, ensuring a comfortable fit. Head size: 51 - 58 cm Bike helmet with detachable sun visor to protect from rain, wind, dust, and strong UV rays. Lightweight, Adjustable Strap