These collet-type control knobs permit the collet nut to be tightened from the top of the knob to allow easy positioning of the knob on the shaft. By comparison, set screw types employ screws that are located on the sides of knobs and so are difficult to access. The ability to tighten the collet-type knob from the top also provides savings in space requirements because knobs can be placed closer to one another. The knobs are tightened 360° onto the shaft to ensure a secure fit, whereas set screw knobs are tightened on one side and can loosen and slip on the shaft. The collet knobs have no exposed metal-work, giving the knobs an appealing appearance.