park tool cc-4 - chain wear indicator

CC-4 - Chain CheckerFeatures:The cc-4 is a drop-in style gauge that measures bicycle chain wearthe laser cut cc-4 accurately measures a long section of chain and strategically comes in contact with the chain in three places, quickly and easily taking the guesswork out of knowing when chain replacement is necessarya worn chain will cause poor shifting as well as accelerate drivetrain wearthe cc-4 works on any 5 to 12-speed derailleur chain (including SRAM axs) and is designed to accurately indicate when a chain reaches .5% and .75% wear, the points at which most chain manufacturers suggest replacementmade in the usa and covered by park tool's legendary limited lifetime warranty