3'' PelletVent Pro Increaser Adapter Tee with Clean-Out Tee Cap - 3PVP-TADX4 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. Built in appliance adapter and increaser for compact applications.