This is a PCB ruler. It's a multi-functional ruler convenient for electronic work. It allows you to measure the size of various electronic components, check SMD components, and measure wiring widths. 【Functions】 ・Ruler (cm, inch) ・SMD R/C/L package size check ・Common Diodes and Transistors package check ・XTAL/OSC package check ・AWG (American Wire Gauge) gauge ・Anode/Cathode indication This is a useful item for designing and repairing electronic circuits, and for hobbyist electronics projects. Thank you.