Inexpensive and reusable, I install these on all my chains so that I can break them and reattach them for cleaning and other drive train maintenance. Years ago, I also purchased the Park tool that makes removing the link a one-second process, although you could also make a small needle nose plier work as a removal tool. No tools needed to reattach. Simple and practical, these make removing and re-installation of drive chains an easy-peasy process. If you care about having a ridiculously clean drivetrain, you need these on all your chains.
A broken chain link on the trail is rare, but it happens from time to time. One of these in your kit is a perfect companion to your multi-tool - - you can fix your chain without having to compromise its length. And it's a LOT easier than trying to drive a rivet back into a link!