The ME1700A tee check manifold is designed to connect two cylinders. The check keeps the two tanks equalized and allows each tank to be changed without disrupting the flow of propane to appliances. For 1/4 in. inverted flare connections on inlet and ¼ in. pipe outlet.Durable brass constructionConstructed with an O-ring behind each inlet ant a disk check seating into the ROS ringInlet: 1/4 in. female inverted flare (2)Outlet: 1/4 in. MNPTIncludes checkPrimarily used for mobile homes, single appliances, recreational vehicles or summer cottages These products contain a chemical known to the state of California to cause cancer and birth defects or reproductive harm. For more information go to www.p65warnings.ca.gov/chemicals