(Note: Measurements are outside max. dimensions unless stated otherwise).19th Century : Gothic design patera with raised centre and shallow chamfered edges. Diam. 21mm. (13/16")Depth 8mm. (5/16")Single central tang on hollow reverse.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.