The PH25 Panoramic Head moves at specific rotational degrees quickly and accurately. In fact, it has two rotational / panning areas. The upper paning control is smooth and can move 360 degrees around. The lower panning control can also move a full 360 degrees and offers the additional feature of predetermined stopping points. The stopping points are achieved by inserting a special knob into one of 5 holes marked with the amount of panning, in degrees. These 5 stopping points are: 15, 20, 36, 45, and 72 degrees. With the knob inserted into any one of the 5 holes and the lower panning control loosened, you can rotate the head and it will mechanically stop over and over again at the amount of predetermined degrees. By removing the spring loaded knob the PH25 has a smooth, 360 degree lower panning control.