Chain Gauge.

Sensible—and stylish, the Chain Gauge is a multi-function bike chain checker featuring an integrated chain hook and wear indicator as well as a handy valve core removal tool. Compatible with most 5-12-speed bike chains and precision-machined for superior accuracy, the Chain Gauge is a stainless-steel insurance policy against premature drivetrain wear. Hang it close to your repair stand with the included ring so you’ll never go too long without checking your chain for wear again, just don’t forget to put it back after cracking a cold one with the integrated bottle-opener.