Park Tool CC-2 Chain Wear Indicator

Use the Park Took CC-2 Chain Wear Indicator to quickly and accurately determine the wear and elongation of any chain. For modern 9 and 10 speed chains, replace chain at or just before the 0.75% readings. For 11 speed chains, replace at or just before the 0.5% reading. Insert the Chain Checker's pins into two links, press the swing arm gauge tight, and check the gauge window for an accurate reading.