Chain wear gauge with a 3in1 design for proactive chain maintenance Proactive wear monitoring: the chain wear gauge shows you when replacement is needed, so you can the chain before it becomes a problem. Durable and reliable: aluminum alloy construction provides longlasting durability and consistently accurate wear readings. Easy to use to regularly check wear on the cassette by timely chain replacement. Multifunctional design: 3in1 tool that serves as a bicycle chain tester, a length measurement tool, and a screw diameter gauge. The screwdiameter function supports M3, M4, M5, and M6 sizes, and the side includes a length measurement function. Easy to use: dualscale design simplifies interpretation of wear. When the wear reaches 0.75 (75%), the chain should be replaced as soon as possible. Practical use scenarios: At home maintenance: quick, regular checks to plan chain replacement and protect your drivetrain. Roadside or ontrail repairs: use the hook function and measurement capabilities to handle onthego adjustments. Bike or workshop applications: measure chain length and screw diameters, and perform quick chain testing as part of installation or service.