I recently came across this nail knob I've been searching for a long time. It is reffered to as standard telephone knob number 4-2. It is pictured in several standard porcelain catalogs but this is the first time I have located one. Elton Gish has one pictured in his collection. The thing that boggles me is what was so special about this design as to use it comparred to the standard two and four groove telephone spools that were commonly used. This piece is marked with a T on the bottom for Thomas & Sons Porcelain Co. This picture shows it in the middle flanked by a two and four groove spools. I have a New England Tel & Tel Co. telephone knob that is similar but smaller. They also has single, two and four groove telephone spools that served the same purpose. Either way it's neat.