With the G19 Gen5 MOS, GLOCK enhances the desirability of the already near-perfect Gen5 model with the addition of the Modular Optic System (MOS). The slide is precision machined to provide a mounting system for popular optic sights. With multiple adapter plates, you can quickly and easily mount miniature electronic sights to the rear of the Gen 5 GLOCK slide, which has front serrations for easier and quicker manipulations.