Ok, the pin I have is four inches from end to end, and just under one inch from side to side. It is made completely of one piece of bent wire, in other words, there is no metal jacket at one end like on a regular safetypin.

As I posted before it is made from some kind of steel and probably nickel plated. Stillwater probably still cairies them, and they were $2.50 when I bought it a couple of summers ago.