The Hillman Bolt, Nut and Screw Gauges are perfect to have handy in every tool box or garage, bringing an industrial-quality measurement tool to your workshop. This gauge tool measures diameter, length and hex size across a myriad of fastener types, ensuring you have the right part for the job every time. Use this gauge tool with a variety of screw types, including flat, round, hex, pan, truss and fillister head screws.