These three stand off insulators were made by Cook Pottery Co. The single and multiple holed white standoff's are marked with a small C in a hexagon which was a Cook Pottery Co. specialities mark. The brown stand off is marked RED DEVIL on one side and PAT APPD FOR on the other. Red Devil was a trade name used by Cook. If you compare the three, They were all made with a mold line on each side and one straight across the bottom which is unique between the three pieces. The porcelain looks to be the same type and quality also.