This Master Flow 8 in. Round Tee is ideal for branching a main line or a branch line with a 90 angle. It works well in heating and air-conditioning applications as well as with kitchen and bath fans. Features: Galvanized-steel construction Sturdy, metal tee is ideal for venting bath and kitchen fans as well as heating and air-conditioning applications Branches a main line or branch line with a tapered, 90 angle Installs with sheet-metal screws Add a reducer after the branch to help ensure proper air velocity Insulate ductwork for system efficiency and comfort Seal seams with code-approved mastic, sealant or duct tape (not included)