Shimano GRX RD-RX810 Rear Derailleur Stabilizer Switch Lever Unit Description: The Shimano GRX RD-RX810 Rear Derailleur Stabilizer Switch Lever Unit is a factory replacement for a damaged or defective part. This lever helps to turn on or off the stabilizer unit that prevents chain slap when rolling over bumps. Features: Includes the rear derailleur stabilizer lever and the plate, or clip, that attaches the lever on the inside of the main body of the derailleur See compatibility tab for a list of compatible derailleurs