The Archaeological North Arrow is used in photographs to show both orientation as well as metric scale (10 cm, 10 one cm, and 1 four cm) in unit excavations. In other words, this is used to show the size and orientations of archaeological photographs. Most scales like this have a 5cm scale where the N is located on the model, but I made a slight miscalculation while whipping it up, accidentally making it 4cm. 

The accuracy of the scale is within 0.3 mm and with some printer calibration, you can probably improve the accuracy.