Carlon B620HR-UPC 4" Round Ceiling Box With Adjustable BarCarlon B620HR-UPC 4" Round Ceiling Box With Adjustable Bar Features:;Designed for use with nonmetallic sheathed cable in accordance with Article 370 of the 1990 National Electrical Code;For Residential, Light Commercial, and Manufactured Housing;Safe, non-conductive, non-metallic, PVC;For new construction;14-1/4" to 23-1/2" adjustable bar;6 integral clamps;Fixture spacing for 2-3/4" x 3-1/2" with grounding lug and screw;4/0 ceiling box;20 cubic inch box