I do a lot of sheetmetal work and these are used to solder joints in the tin. Roofers and sheet metal fabricators use these. The iron is heated on a flame(usually gas),thin held to tin w/ stick of solder flowing to the heated tin. Just to give you an idea. The head is made of copper. I have approx 10 of these in all sizes and shapes. They have been fun for me to collect because I use them. Nice find,Happy md'ing all.