These rulers can be used to measure or plot latitude/longitude coordinates, UTM/MGRS coordinates, and to measure distances in either meters or miles.You will find them useful when you are working with a GPS receiver and paper maps.
Each ruler is designed for a specific scale map. You must use a ruler that matches the scale of your map.
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 four most common map scales an outdoor adventurer will encounter in the Continental United States. Scales included are:
1:24,000 USGS 7.5 minute topographic maps
1:62,500 USGS 15 minute topographic maps
1:100,000 USGS & BLM 30 X 60 minute topographic maps
1:126,720 US Forest Service 1/2"=1 mile forest maps