Giant Screw (GES / E40)
The Giant Screw cap (or Goliath screw cap, as it is sometimes known) is the largest of the Edison Screw fittings. Not as common as either E14 or E27 screw caps, the Giant Screw base can nonetheless be found on industrial lamps designed for applications such as high-bay warehouse lighting, forecourt lighting, or car park lighting.
E40 (Edison, 40mm diameter), GES (Giant/Goliath Edison Screw).
Dual SON & Mercury, Mercury MBF-U, Metal Halide, SON-E, SON-T.