M&G DuraVent 4" PelletVent Pro Round Horizontal Termination Cap - 4PVP-HC Laser-welded, double-wall pipe with a .012" inner wall of 444 Stainless steel Outer wall of .018" laser welded Galvalume Encapsulated O-ring gives secondary seal to system. 1" clearance to combustibles in the US and Canada. Can be turned to direct exhaust output using venturi effect to force exhaust out.