Duct O-Ring, Product Type Duct O-Ring, For Nominal Duct Diameter 4 in, Seal Material Nitrile, Weight 0.02 lb, Maximum Temperature Rating 158 Degrees F, Inside Diameter 4 in, Compatible with Series QF Duct Work, Material Nitrile, Outside Diameter 4 in, Color Black, Compatible with Brand Nordfab, Series QF