NEW Pro-X 51T Rear Sprocket For KTM Husqvarna GasGas Big Bikes “The ProX alloy rear sprockets are all manufactured from high grade 7075-T6 material. The total sprocket is precision cut on fully automated CNC machines using strict tolerances which guarantees perfect fit. The sprockets come with self-cleaning mug grooves. Unlike many other rear sprockets, the specially designed mud grooves are positioned outside the pressure area of chains and sprocket to significantly increase durability.”