4" x 4" Type B Gas Vent Double-Wall Wye with 45-Degree 3" Branch 4GVY34 This double-wall wye with 45 ° 3" branch is used to combine connectors from two or more appliances into a common vent. Branch swivels for alignment. 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