Chimney 69675 6 Inch Dura-Vent Dura/plus Round Ceiling Support Galvalume Painted Black Trim Collar Included Use this round ceiling support when passing through a flat ceiling It includes a built-in, twist-lock starter section for DuraPlus Chimney Round Ceiling Support requires a 14 1/2'' x 14 1/2'' framed opening. Included is a 1 1/2'' wide trim collar. Manufacturer's Limited Lifetime Warranty