Park Tool, CC-4.2, Chain Wear Indicator, Compatibility: 5-13 sp.

The Park Tool CC-4.2 is a precise, laser-cut chain checker designed to measure chain wear (elongation) for 5-13 speed derailleur chains, including SRAM T-Type/Flattop and Campagnolo Ekar. It uses a 3-point contact design to accurately indicate 0.5%, 0.75%, and 1% wear to prevent premature drivetrain damage.