8" Type B Gas Vent Tee 8GVT This tee is used for a 90 ° offset or to combine connectors from two or more appliances into a common vent. Branch swivels for alignment. 3" - 8" feature swivel on male end. For Category 1 gas appliances 1" clearance to combustibles Easy-fit twist-lock design with no fitting hassles 0.012" aluminum inner 0.018" galvanized outer .010†Double-wall aluminum flex inner wall (two-ply .005â€) .018†galvalume outer wall with twist-lock connections.