The Da-Lite Screen Company's Plenum Cover for Da-Lift 15M. The plenum cover is for above ceiling installations where a plenum-rated product is required. The plenums cover helps reduce the amount of heat contained within the space holding the Da-Lift 15M by supplying air from the room below and limiting combustibility. As a saftey precaution consider purchasing a UL-rated plenum cover for your Da-Lite 15M.