This is a premium side facing mount only, for the Umarex HDR50 and the HDS68.
It includes plugs that can be pushed into the holes as a cover. A tiny center hole is built in for easy removal of the covers.
Best secured with two screws. I used 4x50 PZ2 screws, 4mm Diameter, 50mm Length as in pictures.
Follow me and/or check my profile for other Umarex designs I made.