This is a round face plate with 4 evenly spaced screw holes on the front and 4 slots on the back. SP1408-B stamped into back side, just inside the center hole. The 4 screw holes are 1/4" and have countersinks that are 15/32" diameter. The 4 screw holes are 2-9/16" apart on the center line from one hole to the opposite hole.

Dimensions

Outside Diameter: 3-9/16" Inside Diameter: 2" Thickness: 5/16"