Hedman makes three header reducers: 3-Bolt Flange, Ball & Socket, and Uni-Fit. The 3-bolt flange has two flat mating surfaces with a gasket for a leak-free joint. The ball & socket has an air-tight seal without a gasket & mounting flexibility because joining pipes do not have to align perfectly. Uni-Fit accommodates both 3-bolt and ball & socket styles. Ball and socket style flanges do not require gaskets. Necessary gaskets and hardware included.