These rulers can be used to measure or plot latitude/longitude coordinates, UTM/MGRS coordinates, and to measure distances in either
On the front side, the rulers have minutes and seconds on one edge and decimal minutes on the other edge, allowing you to use either notation. On the back side, the rulers have distance in meters on one edge, and distance in either miles or nautical miles on the other edge. Latitude is measured directly with the ruler. But, since a degree of longitude covers a shorter distance as you move towards the poles, the ruler is used on a diagonal to measure longitude. The rulers are printed on a sturdy 20mil white plastic stock for durability.
You must use a ruler that matches the scale of your map.