Used to Hang Fixtures. Cover Accepts Devices With Mounting Screw Centers Of 2 3/4", 3 1/2", and 4 1/16" (70MM, 89MM, and 103MM). Base Has Four Holes For Fixture Studs, Four 1/2" Trade Size Kos, and Raised Section For No-Bolt Fixture-Stud. Use As A Junction or Pull Box With 5736 Blank Cover. Outside Diameter 4 3/4" (121MM). Note: Certified to Canadian Safety Standards For Sale In Canada. When Ordering These Products, Change The "V" Color Prefix to "VC" or The "WH" Color Suffix to "WHC" to Denote The Canadia