This is a SRAM Chainspotter with Washer, Clamp Not Included.
SRAM's chain spotter included with the 2012 Red Yaw front derailleur works so effectively SRAM decided to offer it separately. The SRAM Chain Spotter keeps the chain from falling in toward the frame for worry-free shifting. It virtually eliminates dropped chains. Protecting your frame from damage caused by possible contact from chain drops. The SRAM chain spotter can be adjusted independently of the front derailleur.