642AS-48
Steel rear sprockets are made from carbon steel and electroplated with a satin black finish that resists corrosion; teeth are hardened so sprocket will hold up to many miles, without affecting strength
Fitment data lists this product for 28 model-year applications, including Yamaha YZF R1, Yamaha YZF R1M, and Yamaha YZF R6, with listed model years from 1999 through 2026.