With this dovetail adapter plate from Toni System , it's possible to use a red dot sight on a Glock pistol without a MOS system. The dovetail base plates are designed to be mounted in place of the rear sight. This is possible because this red dot adapter plate features a dovetail, similar to the rear sight.
Included are the screws and pins for positioning.
These Dovetail Optic Adapter Plates are available in different versions for a wide variety of red dot sights:
