3/4" female threaded X 1/2" Barbed Elbow. Use on Performa 263, 268, 269 GE Osmonic Autotrol valves male drain connection ( PN 1002449 )Also, Clack WS1 Drain is 3/4" and could use this elbow.Use with 5/8" O.D x 1/2" I.D. tubing.