S1 helmet Co are a independently and private, Brand, is verwurzelt in the mission skating, longboar Item, BMX and roller derby scenes. S1 helmet Co has now a wide range of helmets, the quickly away well known throughout the industry, which thanks to their approach for style and safety. The S1 box helmets provide up to 5 times higher protection than traditional soft foam skate helmets and offers a superior fit. Small: 53.3 cm 21 cm Medium: 21.5 inches/21.5 cm (L x W x H): 55.9 cm/22 inches Large: 57.2 cm/57.1 cm