Renthal Sprocket Twinring Silver 51T Bi-Metal GroovedThe Renthal Twinring Rear Sprocket is a long lasting durable Off Road sprocket that was developed and tested over the course of 5 years. The unique flat face two piece design keeps weight to a minimum and maximizes durability all while keeping a narrow profile. The outer steel ring is expanded at 200C and then fitted to the aluminum inner before cooling, this process creates a permanent bond while flat socket set screws prevent lateral movement