Nitro Series Disc. Moto-Master Nitro Series discs are the ideal budget O.E.M.-replacement. They offer innovative design and performance enhancement according to Moto-Master quality standards. Made from specially hardened premium-quality stainless steel. NITRO discs allow for high performance braking while exhibiting extremely little wear. Venting slots are integrated into the disc design to aid with cooling and cleaning of the brake pad contact surface. For best performance, Moto-Master recommends using Moto-Master brake pads with the matching pad compound that best suits your type of riding.