The Birzman Chain Wear Indicator will let you know if your chain is worn before affects your shifting performance and more importantly before it damages components in your drive train. The Birzman chain checker is an essential tool that quickly and accurately shows when your chain reaches 0.5, 0.75% and 1% of wear. The indicator comes with integrated chain hooks that help hold chains in place during assembly or repair.Specification:Material: CNC machined stainless steel.Indications: 0.5 / 0.75 / 1.0%.Compatible with single speed to 12 speed chains.