The Park Tool CC-4.2 Chain Checker measures bicycle chain wear. The laser-cut CC-4.2 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 determining when chain replacement is necessary.
The tool works on any 5 to 13-speed derailleur chain (including SRAM® T-Type, SRAM® Flattop™, Shimano® XTR® 12-speed, and Campagnolo® Ekar™ 13-speed chains) or single-speed chain, and is designed to accurately indicate when a chain reaches 0.5%, 0.75%, and 1.0% wear, the points at which most chain manufacturers suggest replacement
