Clear Mercury Lamp 400w Ballast Set * Panasonic Clear Mercury Lamp H400 * New, not tested. Has been stored for a long time. * Iwasaki Electric Ballast H4CC2A352 200v * New, unused since purchase. Clear mercury lamps emit a large amount of ultraviolet light, making them excellent for attracting insects. They are often used for light trapping. Some people have caught large stag beetles with this mercury lamp. It is a highly effective lamp. I was keeping these for light trapping, but I am now selling them.