Simple wall or panel fixing, will fit any screw size under 5.5mm diameter.
Print without supports, both parts A and B are in the same STL but will separate after printing.
If you need a wall plug/dowel to affix this to a wall I have one of those too: https://www.thingiverse.com/thing:4721406
Autodesk inventor files are also in the folder.
Added a smaller version called "Both parts MINI"