Product: Straight Duct Straight Duct Underground Preinsulated Duct System Non-Flanged Round Duct 8″ – 18″ [152 – 457 mm] Diameter ITEM#SizePDF 08-25108” x 90" [203 x 2286 mm] 10-251010”x90” [254 x 2286 mm] 12-251012” x 90" [305 x 2286 mm] 14-251014” x 90" [356 x 2286 mm] 16-251016” x 90" [406 x 2286 mm] 18-251018” x 90" [457 x 2286 mm] Flanged Round Duct 20″ – 48″ [508 – 1219 mm] Diameter ITEM#SizePDFDWG 20-3510F20” x 8’ [508 x 2438 mm] 20-3512F20” x 32” [508 x 813 mm] 24-3510F24” x 8’ [610 x 2438 mm] 24-3512F24” x 4’ [610 x 1219 mm] 30-3510F30” x 8’ [762 x 2438 mm] 30-3512F30” x 4’ [762 x 1219 mm] 36-3510F36” x 8’ [914 x 2438 mm] 36-3512F36” x 4’ [914 x 1219 mm] 48-3510F48” x 6’ [1219 x 1829 mm] 48-3512F48" x 4' [1219 x 1219 mm]