Firestop Support Plate For Nominal Duct Diameter 4 in Gas Appliance Category Category I Material Steel Inside Diameter 4 in Load Capacity Not Applicable Material Thickness 26 ga Compatible with Strapping Size Not Applicable Seal Material Not Applicable Overall Height 1 3/8 in Overall Length 8 1/2 in Standards UL Weight 0.79 lb Overall Width 8 1/2 in For Duct Height Not Applicable For Duct Width Not Applicable Inlet Diameter 4 in Shape Round Base Height 1 3/8 in