These bar end adapters come in 7/8 (~22mm) and 1 variations.
*Triumph owners if your stock handlebars have a threaded boss welded into the end, you can still use these. Youll need 1) a hack saw and 2) a little elbow grease. Lop off the post leaving about 2mm of shoulder of the CRG Bar End Adapter, ditch all the expanding wedge pieces, and itll bolt right on.