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Adafruit PCB Ruler - 6"
The first time you soldered up a surface mount component you may have been surprised "these are really small parts!" and there's dozens of different names too! QFN, TDFN, SOIC, SOP, J-Lead, 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" x 6", this standard-thickness FR4, gold plate ruler has the most common component packages you'll encounter. It also has font size guide, trace-width diagram, and a set of AWG-sized drills so you can gauge your wire thicknesses.
New! As of Sept 15, 2014 we're now shipping v2 which is basically the same thing as the original but Inches are marked with 1/10" rather than the more common 1/8". The centimeter side is still 0.1cm marks.