Exclusive - OZ Racing and Marchesini Bolt Patterns! OZ Racing and Marchesini wheels have a specific rear sprocket bolt pattern and therefore the original sprocket cannot be used. MotoSport's supplier has an exclusive agreement with Renthal sprockets for that particular bolt pattern. As used by many world championship teams in racing, the Ultralight is the chosen product due to its high quality. These CNC-machined sprockets are produced from 7075 T6 material and built to last. Renthal Ultralight™: Renthal Ultralight™ rear chainwheels are manufactured to extremely tight tolerances from a special material developed to withstand the rigors of racing. The 7075 T6 aluminum alloy rear chainwheels are 66% lighter than steel, yet incredibly durable. Their advanced tooth profile, concentricity and accuracy of fit provide maximum power transfer and long-life. Renthal's combination of a very high strength base material and an exceptionally hardwearing surface result in significantly increased chainwheel life over other brands. Renthal Ultralight™ rear chainwheels are 66% lighter than steel. Precision CNC manufactured to extremely tight tolerances. High-strength specially enhanced 7075 T6 aluminum alloy. Computer aided Ultralight™ design gives the maximum reduction of unsprung weight at the rear wheel, to give maximum power transfer. Self-cleaning grooves between every tooth on both sides prevent dirt build up. Renthal Ultralight™ chainwheels are used by more factory teams than any other chainwheel in the world.