Mogul (screw) base light bulbs or mogul base. bulbs have larger screw bases (E39) than the standard, medium (E26) screw base bulbs.

What is the difference between Mogul and medium base?

Mogul bases are the standard for single ended (SE) metal halide lighting. Medium base is very similar to a household incandescent socket and is usually only available for lower wattages.

What size is a mogul base?

NameCodeDiameter (mm)MogulE3939 mmMediumE2626 mmIntermediateE1717 mmCandelabraE1212 mm