A worn chain shifts poorly and wears sprockets at an accelerated rateThe CC-3 is a Go / No-Go gauge designed to accurately indicate when a chain reaches 0.75% and 1% wear - the point at which most chain manufacturers suggest replacementThe chain should be replaced soon if the 0.75% side fits into the chain, before other drive train components also start to wear out fastIf the 1% side fits into the chain, the chain is worn out and should be replaced immediatelyMade from precision, laser cut steelConsider that if you replace a chain because of wear other vital drive-chain components may need to be renewed too10-speed compatible