Keyless medium base incandescent lampholder - Nickel plated brass screw shell, mounting slots accept 3/O or 4/O outlet boxes, accepts most mfgs bulb protective cages - Incandescent lamp holder for use in attics, basements, closets and garages where on/off switch exists - Keyless medium base lampholder - Edison base - Max 660 Watts 250 Volts - Size Dia. 4 9/16"