Some other pieces in my collection which could be used as insulators are actually not. These spools were used for different applications not insulator related. The first two spools were used for block & tackle or pulley uses and winches. They are all unmarked so I have no idea who made them. The biggest spool measures 2 3/8"D X 1 3/8"H. The second spool measures 1 3/4"D X 7/8"H. Elton Gish has one similar on his website and lists it as being made by Globe Porcelain Co. It's an awsome site for porcelain collectors. I love it, very informative. The last two pieces are from a retractable lamp cord assembly. The larger pulley caster piece measures 1 5/8" X 3/8"H. The small spool wire guide piece measures 5/8"D X 5/16"H. These are glazed in a beige glaze and were part of a broken assembly I had. There are other porcelain pieces out there that are mistaken for insulators. Who made them is the question. It could have been an insulator manufacturer, the same as some glass pieces. I had read some place that G.P. Co. had made porcelain door knobs in one section of their factory but since they never marked them how would you be able to tell. The same with other porcelain insulator manufacturers. But would love to find one.