Strike Industries The G.U.M. Universal (Optics) Mount for Glock has the lowest height-over-bore mount without the hassle of cutting your slide or cost of buying an aftermarket slide. The mount itself is secured to the slide via the dove tail with 6 set screws. Other mounting hardware included is 6mm, 8mm and 10mm screws (two of each) that are used to fit and secure most of the popular optics out there. Included are two special screws for Trijicon RMR.