4 inch Insulated GU10 Housing must be used in any ceiling where there is insulation. This housing incorporates a box which creates an air space between the inner fixture and the insulation. Unless there is access from above via the attic, the size of the box makes insulated housings suitable only for new construction applications. One 50 watt, 120 volt MR16 type GU0 base bulb is required, but not included. Trim not included. 24 inch length x 7.75 inch height.