Abstract: These joints are particularly useful for transmitting a flux (electrical, optical, liquid or gaseous) either entirely across the joint, or from one side of the joint to devices mounted on the joint itself that use such a flux. Such devices can, for example, be motors to drive the joint itself. The interlocking bodies are typically but not necessarily circular rings, mounted to a common internal structure that permits each body to rotate about its own axis. The resulting joints can rotate in all directions with a very high angular range--in most cases limited only by the angle subtended by connecting stems used to mount the joint to a base or to mount objects to the joint for motion. Some of these joints have hollow central enclosures for passing flexible wires or tubing to carry the flux, so that the flux can be transmitted across or into the joint with the same high degree of freedom, and yet without slip rings, brushes, or other expensive motionaccommodating components subject to wear.