The first time you soldered up a surface mount component you may have been surprised “these are really small parts!” and there are dozens of different names too! QFN, SOT, SOD and so on, what do they mean and how can you tell how big they are? Now you can have a reference board at your fingertips, with this snazzy PCB reference ruler. Measuring approx 1″ – 7″, this standard-thickness PCB ruler has the most common component packages you'll encounter. It also has a font size guide, trace-width diagram.