1/2x28 to 5/8x24 thread adapter by Gemtech and for use on any suppressor. This custom thread adapter brings 1/2-28 rifles up to 5/8-24 thread pitch, so you may use 7.62mm suppressors in subcaliber role on AR15 and other 5.56mm rifles. Steel construction with sturdy wrench flats, in a dark gunblued finish.