I picked these up after the Shrewsbury show from a guy who had one listed on eBay. They came came from an old 69kv line that ran from the Holtwood Dam to York that was torn down many years ago. Most of these are Ohio Brass Baum Patent disks from around 1920. The gray ones are 1971 Pinco 9" disks and a 1966 OB 10" disk. There are also some 1920s Lockes with the R=00 stamp there too.