The Bolt Size and Thread Gauge has universal standard and metric thread sizes, identifying hardware from #6 to 3/4inch and 4mm to 16mm. Each size has a nut and bolt checker on the same gauge. Drill Gauge: This nut and bolt has 8 different size holes, 4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 1/4inch, 1/2inch, which can Helps you quickly and accurately determine screw size, recommending drill bits or tap sizes required for screws. HIGH QUALITY: Bolt and nut identifier gauges are made from CNC machined aluminum alloy and 12.9 grade hardness tool steel threads, with an anodized surface making them stable and durable. The scale lines are laser printed for easy-to-read bright white markings over a black design. LENGTH MEASUREMENT: This screw size and thread gauge features 4-1/4 inch and 11 cm rulers to help quickly identify the length of bolts, screws, nuts and washers. EASY TO USE: The Bolt Identification Plate is an accurate and easy-to-use nut and bolt thread verifier with external dimensions of 20.8 inches x 4.3 inches, it includes four rubber foot cups on the top and bottom, two preset foot cups. Drilled holes in the top allow you to place it on your workbench or mount it . Colour:black Material:Aluminum alloy Package Contents: 1 x 34 Nut and Bolt 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.