Useful Tool for Chain wear Chain wear indicator shows you when a certain level of wear has been reached, you can replace it before it becomes a problem to keep your bike in good condition and safe. Useful tool to measure the degree of chain wear. How to Check the Chain for wear Fix the caliper in the chain of the bicycle, if wear of 0.75 = 75% is reached, the chain should be replaced promptly. If wear 1.0 = 100% is reached, the chain should be replaced immediately. Chain Hook 2 hook on the top of the integrated chain, which holds the links during assembly, it is more convenient to use, avoiding greasy hands and chain kickback, allowing you to work more efficiently. Thread Diameter Measurement Different sizes of round holes can measure M3 M4 M5 M6 M8 M10 thread, and the Scale can be used to measure its length. Specifications 2PCS Bicycle Chain Wear Indicator Tool. Compatible with all bicycle chains, easy to install and use. Cut: 125 * 42mm. Material: stainless steel, easy to use and transport. Specifications: Material: stainless steel Dimension: 125 * 42mm Weight: 29g Colors: Silver Quantity: 2 PCS Bicycle Chain Wear Measuring Ruler Features: Made of high quality metal, sturdy and durable for long time use. This tool quickly checks stretch and chain wear, it will determine whether a chain is good or bad. Pay attention: 1. Please allow 1-3cm error due to manual measurement. Please make sure you do not mind before purchasing. 2. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Please take the real one as the standard. Thank you! 3.Note: this does not include other things, the color is based on the first picture, and the other pictures only show the effect