Most of us have a box of unidentified machine screws left over from a variety of household projects. Take control of those screws - identify them quickly with this easy-to-use thread gauge. Just find the hole that the machine screw threads into easily, then read the size off the gauge. If you will be tapping threads for the screw, the drill size is included as well. Includes threaded holes for 39 sizes from a #1-64 up to a 5/16" - 32. Measures approximately 1/8" thick, by 5" by 3". Made in USA of engineering plastic.