(Note: Measurements are outside max. dimensions unless stated otherwise).19th Century : Plain shallow dome top with vase shaped tapered neck and flared collar. A solid feel with simple lines.Top diam. 20mm. (3/4")Height top of dome to base of collar 20mm. (3/4") Collar diam. 10.5mm. (3/8")Screw length 30mm. (1 1/8")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.