Renthal Sprockets & Chain Kit. Ultralight Front Countershaft Sprocket & Black Ultralight Rear Sprocket & R1 MX Chain. ULTRALIGHT GROOVED FRONT COUNTERSHAFT SPROCKET. Renthal's Ultralight grooved off-road front chainwheels are chosen by more factory motocross and supercross teams than any other chainwheel on the market. Designed to offer a long lasting front chainwheel in a lightweight design which offers maximum power transfer. They are CNC machined from a cased hardened and core refined 655M13 nickel chromium steel.Mud grooves are CNC machined into each tooth on both sides to allow mud to flow away from the contact points between the chain and chainwheel. This reduces wear and increases the drivetrain lifespan. ULTRALIGHT REAR SPROCKET. Renthal Ultralight rear chainwheels are manufactured to extremely tight tolerances from a special material developed to withstand the rigors of supercross, motocross and enduro 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 hard wearing surface result in significantly increased chainwheel life over other brands. R1 - MX CHAIN - C128. A premium high strength sealed ring chain with excellent impact load resistance designed specifically to withstand the stress found in off road applications where an o-ring chain is desired. This chain is the choice where a combination of high strength, lightweight and maximum power transfer are important considerations. The nitrile o-rings help extend the chain life by retaining the special vacuum injected grease near the critical pin area. Average Tensile Strength: 7644 lbs. Number of Links: 120. Master Link included.