Carlon ceiling box extender round tubing 3.2 cu-in 4 in diameter x 1/2 in thickness single gang PVC Blue includes: cover UL listed for light fixture support. Half inch raised round high impact lightweight PVC. Used with nonmetallic sheathed cable in octagon boxes. Supports 50 pounds. Ul listed. Box Plaster Ring; Round; Raised; 4-Inch Diameter; 1/2-Inch Raised; 3.2 Cubic-Inch Capacity; Non-Metallic Material; Blue Color; UL Approval.