Glock 19 Gen 5 MOS 9mm Semi-automatic Pistol With over 20 design modifications from its Gen 4 predecessor, the G19 Gen 5 is proof positive that even the most refined polymer pistol in the world can get better. Among the most notable changes is the Glock Marksman barrel with enhanced polygonal rifling that delivers a better gas seal and less fouling. The Gen 5 preserves the reversible magazine catch of the Gen 4, but goes one step further by incorporating a truly ambidextrous one-piece slide lock. That's a nice upgrade for you lefties out there. The magazine and mag well have also been overhauled. The magazine now features an orange follower so you can visually identify empties, as well as an extended lip for grip. The mag well has been flared for faster reloads. The finger grooves are now gone, and the front strap features a cut-out for extracting the magazine. Bottom line: it's the same Glock you know and love. It's just a little more shooter-friendly now. The Gen5 MOS takes it a step further by adding easy red dot compatibility. The Modular Optics System This model features the Modular Optics System, which makes it easy to mount optics without custom machining of your pistol's slide. The slide features a factory-cut removable plate that can be taken out and replaced with mounting plates-no custom machining necessary. Includes mounting plates for most popular red dot optics. Modular Optics System (MOS) makes it easy to mount optics without custom machining of your pistol's slide NEW Marksman barrel with enhanced polygonal rifling NEW ambidextrous one-piece slide lock makes it more lefty-friendly NEW orange follower in the magazine for easy identification of empties NEW extended bottom lip for easy magazine extraction NEW flared magazine well for easy reloads NEW straight-grip design fits all hands NEW front strap cut-out for extracting magazines NEW rounded front of the slide for easier holstering New nDLC finish provides tough