Antique Tregoning Porcelain Screw In Electric Plug & Perkins Mate Socket RARE. In aged used nice overall condition, unmolested with original patina finish. Rare screw in plug as found with quick connect Perkins Socket (not a light socket). Tregoning plug appears to have a mold mark on one edge (has glaze except center of mold breakaway). 660 W 250 V Tregoning Plug, Perkins Socket June 13,1899 Patent, 250 V, 50 C. A nice addition to an antique electric fan, toaster, or other electrical appliance. Please see all images for a pictorial description and ask any questions.