Nut and Bolt : Bolt size and thread gauge bolt size and thread gauge is an accurate, easy-to-read, durable bolt and nut identifier gauge that quickly measures bolt length and nut diameter, separating metric from rigid thread sizes, saving you time and increasing your efficiency. Bolt and Nut Identifier Gauge: Nut and bolt recognizes nuts and bolts in 28 sizes, 14 inch & 14 metric. Each size has an external thread for nuts and washers and an internal thread for bolts and screws, distinguishing between different nuts and bolts. Durable: Nut and bolt is machined with carbon steel. bolt size and thread gauge can be installed in your toolbox or wall. We have provided you with reserved holes for hanging. No need to drill again. Two Sizes: Nut and bolt gauge comes in inches and centimeters along the help you quickly identify different sizes of threads. Colour:Black Material:carbon steel Package Contents: 1 * Nut and Bolt Checker Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.