3" to 4" PelletVent Pro Black Appliance Adaptor/Increaser 3PVP-X4ADB This appliance adaptor/increaser is used to attach to an appliance outlet allowing for easy pipe connection. Allows connection of 4" vent to 3" appliance outlet. Seal adaptor to appliance with high temperature sealant. Use with pellet oil corn and bio-fuel appliances Laser-welded super ferritic stainless steel inner walls and galvalume outer walls Outer diameter is 5/8" larger than inner diameter 1" clearance to combustibles No additional gaskets or sealants needed The precise fit of twist-lock connections is fast secure and leak resistant. Adaptability is provided by swivel elbow connections and multiple termination options Laser-welded double-wall pipe with a .012†inner wall of corrosion resistant stainless steel and a .018†laser-welded galvalume outer wall. Painted black exterior available. Primary metal-to-metal connection seals joint. Encapsulated O-ring provides a secondary seal.