KMC Z610HX 3/32" Master Link
Same master link as included with each KMC Z610HX chain.

Ideal if you are planning on running two ratios regularly, rather then break and re-assemble your chain, simply add a second master at the required joint. Pop both master links, remove extra links and re-attach with one single master. If that's too complicated or just plain unnecessary, its not a bad idea to have a spare...