This is a replacement for the ZWO TC40 Tripod Spreader. It includes both the spreader and the knob. They can be used together or either component can be used with the original ZWO piece (original knob and 3D printed spreader or vice versa). The knob is threaded and holds well, but remember, it is a 3D printed thread and is not as strong as a metal nut. Hand tension only.