The Glock 19 GEN 4 Modular Optic System (MOS) allows the shooter to mount the red dot sight of their choice quickly and easily with minimal tools. Four adapter plates are provided as well as a cover plate when no optic is mounted. Versatile and rugged, the Glock 19 GEN 4 MOS simplifies the mounting of popular optic sights without costly custom machining of the pistol’s slide. Comes with all of the usual factory accessories, including box, manual, lock and three 15 round magazines. Plate 01: Eotech/Docter/Insight/Meopta – Plate 02: Trijicon RMR – Plate 03: C-More – Plate 04: Leupold Delta Point. Made in the USA.