Here is the best I can do taking this picture. The glaze on this little knob is kind of thick, but I hope you can make out the dollar sign embossing at the 6-o'clock position. Much easier, with a little studying to make this out in hand. Taking pics of embossing can be be tricky and you sometimes have to keep re-positioning until you get the light to cast on the insulator just right. Anyone know which company produced this embossing or ever seen it before? Updated:::Thank you Elton Gish for correcting me on this. Elton says: It is not a dollar sign. It is a U and S overlaid. It is the marking used by U. S. Electric Porcelain Co. in Findlay, OH. They made standard porcelain (knobs, etc.)