COMPATIBILITY: This chain checker is designed to accurately measure when the chain reaches a .75% or 1.0% stretch and decide the necessity of chain replacement. Compatible with 7 to 12 Speed Chains including for Shimano Sram Campagnolo KMC and other brands. EASY OPERATION: Simply place the checker onto a segment of the chain then see whether the chain checker lies completely flat on the chain. If so, replace the chain. However, the chain is still good to use if the chain checker sticks upright at the 0.75% end. PRO QUALITY AND COMPACT: This precision laser-cut tool is well built and constructed with pro-quality material, forethought, and care for longevity and is easy to store.