This 2.25-inch standard base phenolic socket is made for heavy-duty use. With a metal-lined socket, it is rated up to 660W and 250V. The bracket on the bottom is threaded 1/8 IP, so it will fit onto any standard threaded 1/8 IP lamp pipe. This medium base socket is keyless (does not include an on/off switch) and is best used with chandeliers, floor lamps with wall switches, or touch base reading lamps.