New rear sight replacement mount. The closest you can get to the slide without cutting or having a MOS ready Glock.

This mount fits best with the RMS, RMSw, SMS, SMS2 or Jpoint.
The RMSc and SMSc will fit. Due to their compact design, the sights are narrower than the mounting plate.

Simply remove rear iron sights, slide in the packaged receiver and screw down the sight to the mount and receiver.