Here is are some different types of Neon Sign electrodes. The first is a glass sign bushing made by Pyrex under the patent by samual C. miller 2,206,913 July 9,1940. The next three are different electrode types based on the patent by Otto A. Rieman 2,072,042 Feb 23,1937. The first is C.G.W. No. 300 (Corning Glass Works) wire clip screw on, Next is McMahan No. 300, single push on clip, off clear (McMahan-FMS Corp MI),Last is McMahan No.300 screw on clip clear glass.