Renthal Sprocket Rear Silver 52T Alloy 7075 T6 Grooved Cap De Formentor Lighthouse Jonathan Bond Photography. Renthal sprockets feature a specially developed nickel chrome molybdenum alloy steel which is case hardened and core refined to give the ultimate combination of strength and hardness. Grooved sprockets have cut outs at the bottom of the tooth to allow the escape of mud that would otherwise be trapped between the sprocket and the chain. This prevents tension from being placed on the chain and the resulting accelerated wear Using advanced computer engineering alongside CNC machining, Renthal consistently achieves perfect concentricity, fitment, load dispersion and uncompromising strength whilst ensuring maximum power delivery. Features: CNC Machined To account for the extremely high tolerances required for engine components, Renthal utilises in house CNC facilities to accurately machine each individual sprocket to the tightest tolerance possible. Core Refined Core refined 655M13 Nickel Chrome Molybdenum alloy steel provides the ultimate combination of strength and hardness. Mud Grooves Self cleaning mud grooves between every tooth on both sides to help prevent dirt build up. Case Hardened The case hardening process ensures that the sprocket has the longest service life possible. Each sprocket undergoes heat treatment to harden the surface.