This Replacement Pedal Office Chair Component for the Chair and Stool allows your chair to be heightened or lowered. The mechanism allows for a 17-degree angle in the back of your chair and a 25-degree angle forward. The part comes with one piece that is black and includes one pedal to adjust the height of the chair and one component to adjust the front and back angle of the chair. The center hole is a standard size for chairs and stools.