The SR45 is the .45 ACP pistol in Ruger's SR family. Owners who want a dot on it without sending the slide off for milling can use EGW's dovetail mount.
Why a dot on a .45
A red dot puts the aiming point and the target on the same focal plane, so you see both sharply. During recovery from recoil the dot is easy to track back onto the target.
The mount
EGW designed it to lock into the rear dovetail, with a deck for Trijicon RMR footprint optics. The design is shared with the SR9 and SR40.
Fitting
Remove the rear sight, slide the mount in, then attach and zero the optic. Before the first range trip, check that the optic screws are tight and the mount sits centred.