1/4" flathead driver bit should be compatible with most camera tie-down screws. Printed tip dimensions should come out to 11.1mm x 1.8mm and are easily sanded down if too thick.
More adaptable than the standard stubby flathead, allowing skinny access to those hard to reach capture screws on tripod plates and baseplates.
A great camera assistants tool!
Check out the more specific O'Connor Tie-Down Driver Nub
and gimmicky Camera Screwdriver / Belt Buckle