A worn bicycle chain causes poor shifting performance and accelerated wear on drivetrain components, causing more expensive problems.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® Ekar13-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.Some drivetrain manufacturers have unique recommendations specific to their components, always double-check to be sureMade in the USA and covered by Park Tool's legendary limited lifetime warranty.