Park Tool CC-2 Chain Wear Indicator

Quickly and accurately determine the wear and stretch of any chain. Compatible with all bicycle chains 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