(Note: Measurements are outside max. dimensions unless stated otherwise).
18th Century : Plain thread escutcheon.
OUTSIDE
Height 11.5mm. (7/16")
Width top 6mm. (1/4")
Width base 6mm. (1/4")
Depth 2.5mm. (1/8")
Thickness (variable) 1mm. (1/16")
KEYHOLE
Height 9.5mm. (3/8")
Diam. of hole 3.5mm. (1/8")
Width at narrowest part of neck 2mm. (1/16")
Width at base of taper 3.5mm. (1/8")
Usually glued in.