A keyhole recess for picture hanging flush to the wall.
Ref. 35/0 - No.8 & No.10 screw heads.
Not suitable for grooving applications.

Specification:
D=9.5 mm
D2=4.5 mm
S=5.5 mm
C=4.5 mm
OL=40 mm
Shank Diameter=1/4 inch