Helps you decide when it's time to change the chain - if your wear is above 0.5 (10, 11-speed) or 0.75 (7/8/9-speed) it's time for a new chain! You can run single speed or IGH chains to ~1.0 wear.

The CC-2 is compatible with most single-speed and derailleur chains. For single-speed chains, replace chain at or just before the 1% reading. Check with manufacturer for specific replacement instructions. Use the CC-4 for SRAM® AXS 12 speed road chains.