9Transport Bike Helmet with Integrated Rear Light. Universal Size for Adults (adjustable to heads between 58 – 63 cm). Universal size with regulating wheel at the back of the helmet to adjust the helmet perfectly to the head. It comes with a visor and a triangular light at the back of the helmet with battery CR2032 to provide visibility and safety during the ride. Material: External shell made from PC (resistant and solid material) and Interior made from EPS (very light material with capacity to absorb impacts and provide heat insulation).