Chain Spotter:~ A simple yet elegant method ensures accurate performance while protecting your frame. The 2.5mm included hex screw fits right in the 4mm hollow threaded derailleur mounting bolt. Compatible with all SRAM road groups. If your frame does not have a braze-on hanger, you must also buy the Red Braze-On clamp sold separately.
• For frames without braze-on, you must buy SRAM Red braze-on adapter separately
• The 2.5mm hex mounting screw fits right in the 4mm hollow threaded front derailleur mounting bolt
• At a mere 12g, the SRAM Chain Spotter is compatible with SRAM RED-2012, SRAM RED, SRAM Force, SRAM Rival and SRAM Apex braze-on braze-on front derailleurs