4" inch, 4RV-TK, 4 Piece, Round, Type B Gas Vent Termination. Kit includes top flashing, storm collar and draft hood connector. Constructed from galvanized steel, which resists corrosion. Type B gas vent kit for gas appliances in residential and light commercial and industrial applications. Outer pipe has internal spacing bends, to assure a uniform insulating air space between pipe walls. From the Manufacturer 4" inch, 4RV- TK, 4 Piece, Round, Type B Gas Vent Termination. Kit includes top flashing, storm collar, and draft hood connector. Constructed from galvanized steel, which resists corrosion. Type B gas vent kit for gas appliances in residential, and light commercial, and industrial applications. Outer pipe has internal spacing bends, to assure a uniform insulating air space between pipe walls.