The Pocket Engineer - Wallet Ruler and Conversion Reference

Always be ready to measure, calculate and fix anything with The Pocket Engineer.  Packed with features in laser-cut stainless steel the size of your credit card: 26 unit conversions, 7 equations, and 10 physical constants to save you time looking up references in mechanical, civil, electrical, industrial, nuclear, and materials engineering. Doubles as a wallet ruler and protractor. Photogrammetric ruler to calibrate length and tilt in images when used as a scale in field or lab work. Pipe inner diameter measurement from 0.25"-1.25" and machinist scale with 10-mil resolution. Here's how to use me!