New Old Stock WGP 3 way line barb, fits classic WGP 3 ways, brass, one included. Thread size is 6x40 which is standard 3 way barb size.
Outer diameter at barb is 0.118 inches and inner diameter of barb end is roughly .044-.050 inches.
Stock fitting for many of WGP's pneumatics including 3 way and other items. See photos.
Fits Autococker 1/8th inch ID hose but is tight.