Firestop Support Plate For Nominal Duct Diameter 3 in Gas Appliance Category Category I Material Steel Inside Diameter 3 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 7 1/2 in Standards UL Weight 0.57 lb Overall Width 7 1/2 in For Duct Height Not Applicable For Duct Width Not Applicable Inlet Diameter 3 in Shape Round Base Height 1 3/8 in