The 10023400RT100 Buttweld Reducing Tee Fitting has 4.0 inch outside diameter main ports with a reduced size 1.0 inch O.D. branch port and 0.065 in. wall thickness. Reducing tees are a common component of vacuum piping systems and are used to provide a reduced sized 90 degree branch. Series 23 vacuum buttweld fittings are constructed with welded, drawn, and annealed 304 stainless steel tubing for applications where minimizing the number of sealed joints is critical. Stainless steel vacuum tubing offers low outgassing under vacuum conditions, is chemically resistant, annealed for consistent leak free welding, and has minimized corrosion concentration points. Series 23 fittings are designed for internal socket type welding or external buttwelding.