Reflectors are fitted above light troughs to reflect the light from LED, Cold Cathode or Fluorescent light units. Used together these units are normally positioned at the perimeter of a room for wash lighting or to make two different levels with background lighting. They offer an accurate, consistent and simple method of forming this using the same suspension material and jointing process as plaster board ceilings. The main advantages of using a GRG reflector are the ease of installation and the ease of getting a good finish in an inaccessible location.