Duct Start/Take Off Collar Boot Style Speedi-Boot Hanger Collar Diameter 4 1/8 in Collar Connection Height 4 1/8 in Collar Connection Width 6 3/8 in Material Plastic Compatible Register Height 6 3/8 in Compatible Register Width 6 3/8 in Duct Size 5 in Cap/Collar Material Plastic Product Type Register Boot Damper Type Manual Standards UL 2043 Classified