I have a huge collection of edison base fuses. Just about every electric company had their own brand. They even had Neutral Block Offs that would screw into a plug circut to block it from use. Sort of similar to the lock out tag out policies we have today. I have several of these and find them very hard to find. Some are made just like a fuse plug and some are completely porcelain. Either way they are really neat. From Left to Right back row: BUSS all porcelain, BUSS black glaze, MURRY grey porcelain, M.E.T. Device Corp. Brooklyn NY all porcelain, Front Row: Bryant "Not A Fuse" green ink, Bryant "Not a Fuse" cobalt glaze, Bryant "Not A Fuse" black ink.