This one is almost pyramid-shaped. It is recessed-embossed on top with the word "Thomas". I don't know much about porcelain, so please correct me if I'm wrong, but I believe this is a U-209.

This piece is one of a few interesting porcelain insulators I was lucky enough to have in my possession for just a few days before delivering them to their new owner. I liked them so much, I decided to photograph some of them and post them for reference.