Because rugby is such a fast paced and physical game it's a good idea to wear protective headgear for added protection against serious injuries. Because the rules of rugby forbid any rigid or hard equipment the helmet must not be made with a hard outer shell. Most rugby helmets are made out of lightweight foam padding and are designed to cover the whole head, including the ears, but are designed not to hamper your hearing. Ventilation holes are included to keep you cool and the helmets are fully adjustable. Make sure your helmet is comfortable and fits snugly, so it doesn't move around on your head on impact.
