(Note: Measurements are outside max. dimensions unless stated otherwise).18th Century : Knob with worn engraved edge decoration and concave top. Top diam. 16mm. (5/8")Height 11.5mm. (7/16"). + threaded shaft 14mm. (9/16")Collar diam. 7mm. (1/4")Original believed to have come from French Lady's Bonheur-du-Jour.For suitable backplate if required, see "Backplates" section.It is recommended that if selecting screw thread option, a pilot hole is drilled and pre-cut with a steel screw of slightly smaller size before screwing in the casting to avoid shearing.