Sine bars set up an exact angle that angled workpieces can be checked against to determine whether they have been accurately machined. They are typically used to measure angles of 60° or less. Sine bars consist of two precision-ground cylinders set parallel at a known distance (5" or 10" center-to-center) near the ends of a precision-ground bar. Spacers such as gauge blocks or slip gauges are used to raise one end the bar to a specific height to create the desired angle. Workpieces can be set upon the bar and measured with an indicator gauge to check whether the workpiece angle matches the sine bar angle.