Abstract: An improved supply line fitting, installation method and technique for direct installation in the supply lines of a distribution system. An angularly flanged, resilient insert barb being force fitted into an opening in a supply line, seals the opening at three points upon being compressed by an external sealing washer and locking assembly. The locking assembly utilizes an intermediate pressure plate for smooth, distortion free compression, providing a positive internal and external seal of the supply line, and locks the fitting at any point along it's 360 degree rotational axis in preparation for interconnection to a final output device.