(Note: Measurements are outside max. dimensions unless stated otherwise).19th Century : Gothic design upholstery nail with raised centre and shallow chamfered edges.Diam. 13mm. (1/2")Depth 5.5mm. (3/16")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.