I've had these bushings a long time. These are made by Federal porcelain Co. Chicago, Illinois. They had a patent for this design U.S.830,501 0/11/09. I think they are really neat with the embossing all around the top. Federal Electric Co was formed in 1901 and made electric lighted sign letters for stores etc. They were the first to have a patent U.S. 744,331 11/17/08 for the electric lighted sign. They invented the threaded porcelain bushing to use in these signs plus others. Around 1915 they started making sirens and speakers for buildings, vehicles etc. and had a really cool patent for a police siren U.S.2,200,222 11/5/1940. In 1956 they became the Federal Sign and Signal company and changed their name again in 1975 to the Federal Signal Corp. Nowadays they make road marking and signal signs. The small bushings I have are marked A F.E. Co. CH I (size number) Pat. 9 11 06. The sizes in the top picture are number 2 and the last two 1 1/2, 1. The bottom one is a huge bushing measuring 2 3/4 X 1 1/2. It is marked differently. A F.E. Co. Chicago 6 Pat. 9-11-06.