4" PelletVent Pro Black Increaser Tee with Clean-Out Cap 4PVP-T3B1 This increaser tee with clean-out cap attaches 3" pipe to branch and 4" pipe to body. Used for a 90 ° offset. Branch swivels for alignment. One piece unit incorporates removable twist-lock Clean-Out Tee Cap. 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.