This is the newest version of Glock factory mag loaders and is sized for a majority of their models. If your gun is a Gen 1 2 3 4 or 5 model 17 17L 18 19 22 23 24 25 26 27 28 31 32 33 34 35 or 45 then this is the right loader for your mags. Double stack 9mm, .357, or .40 all work.