To alleviate poor shifting and uneven drive train wear, most manufacturers recommend chain replacement at or before 0.6% stretch. With the Unior Professional Chain Wear Indicator, you can quickly and accurately determine the wear and stretch of any chain. Simply insert the chain checker’s pins into two links, press the swing arm gauge tight, and then check the gauge window for an accurate reading.
Professional-grade tool for checking bicycle chain wear
Works with any conventional bicycle chain
Gauge window provides an easy to read, accurate measurement
Easy To Use
Familiarity: I've used it several times
This thing is super easy to use and not complicated at all. Spin the dial until it stops and then look at the reading on the dial. If it doesn't stop spinning your chain is REALLY stretched! Solid craftsmanship and design that should last a long, long time. Not cheap plastic.