Renthal Grooved Front Countershaft Sprocket Ultralight Rear Sprocket & R1 Works MX Chain Kit. FRONT COUNTERSHAFT SPROCKET. Renthal Front Chainwheels feature a specially developed a case hardened and core refined 655M13 Nickel-Chrome-Molybdenum steel to give the ultimate combination of strength and hardness. . Ultralight REAR SPROCKET. Unique flat face design keeps weight to a minimum and means the Ultralight is as narrow as a regular chainwheel Inner Ring is high strength ultralight 7075 T6 Aluminum. Outer Ring is Electroless Nickel Coated steel Outer is expanded at 200C and then fitted to inner, creating a permanent bond for the life of the sprocket Precision CNC machined to extremely tight tolerances Flat socket head screws add additional strength to the chainwheel during side impacts Self-cleaning mud grooves between every tooth on both sides help prevent dirt build up .. R1 - WORKS MX CHAIN. R1 Works Chain from Renthal is a high-strength, non-O-ring chain with excellent impact load resistance designed specifically to withstand the stress found in offroad applications. This chain is the choice where a combination of high-strength, lightweight and maximum power transfer are important considerations. Shot-peened alloy steel side plates for high-tensile strength and maximum impact load resistance. Chamfered inner links to help reduce the chance of chain derailment. Extended bushings to reduce friction between inner- and outer-link plates. Shot-peened solid rollers and chromized pins help to extend service life. Gold-anodized side plates help prevent corrosion.