DuraVent DVL Double Wall Black Tee Connection With Cleanout Cap Size:8 in. This is most commonly used This is most commonly used when you need to transition from a flexible liner to a pellet vent pipe to pass through a combustible area where reduced clearances is required (Rock Vent Pellet Pipe has a 1" clearance to combustibles) High efficiency appliance 2020 EPA approved DuraVent DVL Double Wall Stove Pipe Tee With Cleanout Cap is used to turn a horizontal pipe into a vertical stove pipe Use the tee connection in conjunction with a double wall stove adapter to connect the tee to the back of a stove to route the stove pipe to the chimney or chimney pipe