Shimano Chain Wear Indicator Tool TL-CN42The Shimano TL-CN42 chain wear indicator tool is designed to measure chain stretch on all ½” pitch chains. Ie, 8, 9, 10, and 11 speed chains, be they Shimano, Sram, Campagnolo, KMC, or other. Simply insert back end of the chain wear indicator into the chain and lower the front end down. If it does not enter, your chain has a sufficient lifespan for continued riding. If it does lower however, your chain has stretched too much and is no longer recommended for use. Should you continue to use this worn out chain, the chainrings, pulleys, and cassette will suffer!689228988491