A worn bicycle chain can cause poor shifting and in time can even cause excessive wear to the derailleur and rear cogs, causing a much more expensive problem. That's why bike component manufacturers recommend chain replacement at regular wear intervals. The Park Tool CC-3.2 is a go/no-go gauge designed to accurately indicate when a chain reaches 0.5% and 0.75% wear (or "stretch"), the points at which most chain manufacturers suggest replacement. The CC-3.2 is long, accurate, and features permanent measurement markings. The CC-3.2 works on most derailleur chains* from 5 to 12-speed. An accurate way to check for wear of roller and pin on chains 1% of wear is enough to affect chainrings and sprockets, and allow shifting performance to deteriorate Just insert the chain Checker's pins into two links, press the swing arm gauge, and then check the gauge window for an accurate reading Reads wear from 0.25% to 1% 10 and 11-speed compatible For Sram SRAM® Flattop™ and SRAM® T-Type 12-speed chains, click here