Slip Uno adapter to convert old lamp to accept a harp and spider fitter shade Fits directly over a lamp socket (found on lamps often purchased at many popular retail stores). Adapter then attaches to the harp Adapter fitter is 1 and 7/16 inches in diameter Harp Converter for UNO/Euro Fitters by Home Concept - Take your antique lamp UNO socket and convert it to a harp/finial lamp shade attachment - 1 7/16 inner diameter