Vapor Barrier Ceiling Box, Round, Noryl Plastic, 4-In. Vapor barrier boxes prevent unwanted penetration of exterior air and help maintain the existing interior environment from elements outside the structure. RACO nonmetallic vapor barrier cable boxes provide the installer with a cost alternative that is ligh Highlights: 4 Inch Round Noryl Plastic Flush Bracket 1/2 inch Setback 4 Non Metallic Cable Clamps 28.1 CU IN Capacity Base Mounted Ground Screw Full L Shaped Ground Strap Slotted 45 degree mounting holes on inside The metal ground strap runs from one fixture screw to the other for a safer installation and provides convenient access to both ground screws Features 4 Inch Round Noryl Plastic Flush Bracket 1/2 inch Setback 4 Non Metallic Cable Clamps USA SHIPPING estimates delivery times and we work to get your item to you as quickly as possible and within those times, but please know it may take slightly longer than the estimate.