Mate your fastener and countersink perfectly for a secure hold with these Starrett gauges. They are often used in vehicle and metal manufacturing to check the top diameter and countersink angle of a hole. When the conical probe touches the hole’s angled walls, the diameter will display on the dial. You can verify the countersink angle based on how snug the probe fits into the hole. Even when you lift the gauge out of the hole, your measurement will stay on the dial until you press the reset button.

Choose a gauge with an angle that’s equal to the angle of the countersunk hole you’re trying to measure.