Vortex 452AK-40 40-Tooth 520-Pitch Hardcoat Rear Sprocket Lightweight F5 aluminum racing sprocket 100 percent CNC manufactured in the USA Specially formulated alloy per Vortex specifications Polytetrafluoroethylene (PTFE) black hard coat increases wear resistance Unique tooth design increases sprocket longevity; Vortex patented sprocket design is unlike any other sprocket