3" PelletVent Pro DSA Aluminum 7/12 - 12/12 Roof Flashing 3PVP-F12DS This roof flashing is used with metal or tile roofs and helps provide an effective evacuation point for chimney exhaust while also keeping out debris and water . Made of dead soft aluminum. 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.