Item Name: Chain Wear Indicator Chain Replacement Gauge Check Ruler Bike Chain Checker. Made of stainless steel materialEasy to useA worn chain shifts poorly and wears sprockets at an accelerated rate. 0.75% and 1%, the points at which chain experts suggest replacement.Compatible with all chainsSize: approx. 14cm x 4.8cm/ 5.51" x 1.89" (LxW)Brand new & high quality.Package Included:1pc x bicycle chain checkerEasy to use.With the wheels of the bike on the ground apply a light pressure with the right hand to the pedal to slightly tension the chain.Then apply the tool to the top (the drive side) of the chain.If the tool gauge drops in flat to the chain then the chain is worn past the respective indicator and needs replacing. *Please make