These are for large Victor multiparts and were used with M-4325, and M-4321 stiles one has a threaded top the other has an insert that would have been cemented to the pinhole this is the Largest porcelain pin base design known . asking $40 each + postage. the porcelain bases are both mint I currently only have these two but if there is enough demand I could go back and pack three or four more out .