Flat Cover | 4 in Octagon Back Plate With 3/8 in Fixture Stud; (2) 1/2 and (2) 3/4 in Knockouts | For Use in Insulated Ceilings | Passive Infrared Sensors That Automatically Control the Lights in an Area. These Sensors Detect Heat From Occupants Moving Within an Area to Deterine When the Space Is Occupied. Combines a Maestro 0-10 v Dimmer With an Occupancy Sensor. Controls 1-10 VdcFurbay Electric Supp