Dura-Vent type B 3 inch diameter gas vent tee. For installations involving two gas appliances you will not find a more convenient tool than a Dura-Vent Type B Gas Vent Standard Connection Tee. With this handy venting accessory you can conveniently connect two appliances to a single vent and create a ninety-degree offset. The male end of the branch even swivels for easy alignment.