Hello, I found these in a box with a bunch of clear insulators. Not sure what they are. They seem to be made from ceramic or something other than glass. There are no markings on the solid colored one.
Thank you so much.The first one is usually called Bakelite, a type of fibrous plastic material. Usually they went on lines where glass could get damaged easily.
The second is porcelain (the preferred term over ceramic). The marking isn't complete, it's from the THOMAS company in Ohio, probably 1930s-early 1960s. That's a neat uneven glaze.