Renthal 420-520-13GP 13 Tooth Front Sprocket Case hardened and core refined 655M13 Nickel-Chrome-Molybdenum alloy steel to give the ultimate combination of strength and hardness Renthal's combination of a very high strength base material and an exceptionally hardwearing surface result in significantly increased chainwheel life over other brands Feature self-cleaning mud grooves between every tooth on both sides help prevent dirt build up Precision CNC Machined to extremely tight tolerances Developed to withstand the rigours of supercross, motocross and enduro racing