The Glock 19 is the compact 9mm of the Glock line, sized between the full-size 17 and the subcompact 26, with a 4.02 inch barrel and a 15 round magazine. Gen 5 guns drop the finger grooves, add an ambidextrous slide stop and use the Glock Marksman Barrel, while MOS models cut the slide for a red dot. Listings cover Gen 3, Gen 4 and Gen 5 guns in standard black, Cerakote and engraved finishes, plus optics-ready MOS builds and rebuilt law enforcement trade-ins. Barrel length and capacity stay the same across most of them, so the differences are sights, slide cuts and finish.