Dirty Dog helmets are designed for maximum safety when you need it most. Constructed with a protective outer shell made from PC or high impact ABS. These shells give the helmets durability, weather resistance & are easy to clean. Underneath the outer shell is EPS (expanded Polystyrene) which makes up the bulk of the internal mass of the helmet for the absorption of impact & temperature control. The ergonomic design of Dirty Dog helmets eliminates wind resistance enabling you a smooth unhindered ride.