The GamChek is a quick and easy way to check your dimmer output for power, correct polarity and ground. It is able to hang from the attached lanyard, so it can conveniently be hung around your neck. 3 neon lamps tell you instantly if you have a live power outlet and will also alert you if there is a problem with polarity and if there is a correct ground path. Label on the back on the unit indicates circuit continuity.