Center gauges, also known as fishtail gauges due to their resemblance to fish, come to a point angle with a fluked tail end that comes to the same point angle. These gauges are constructed of steel and are often graduated along one or more edges and etched or printed with sizes or conversions. They are commonly used for hand-grinding threading tool bits on a bench grinder and are also used with tool and cutter grinders. When the tool bit has been ground to the correct angle, they can also be used to set the tool perpendicular to the workpiece.