Adafruit 6" PCB Reference Ruler v2
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, 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.