That's an E40 Mogul base lamp. Mercury Vapor should theoretically be replaceable with Metal Halide, as the metal halide is a variation of the Mercury-vapor lamp.
khyberkitsune Reviewed by khyberkitsune on . 400w lighting inquiry???? bought these ballast and lights off of craigslist. they came out of a catholic school gym. they are mercury vapor. but they are also hid's my only question s how do i figure out what type of bulb to replace the mercury vapor bulb, cause it might just be me but the bulbs socket end looks to be a bit bigger the n other hid bulbs. idk maybe not though you be the judge, any help would be greatly appreciated. i will post picks if i can get the posting figured out. oh yeah the light/ballast is made Rating: 5