This will allow you to mount a Sig Romeo Zero directly on to your Glock standard frame size slide (G17, G19, G34, etc.) This red dot has an integrated rear sight, but we can set this low enough and it is small enough that the integrated iron sights will cowitness with your factory iron sights. This program leaves the factory rear dovetail. The Sig Romeo Zero comes with a set of both M3 and M4x.07 screws. This program will drill and tap for the M4x.07 screws.