This instrument is used to measure distance accurately on maps of ali types. It is particular value to motorists, cyclists, hikers, architects, schools and offices. Direction for use: Set the pointer to -0- by turning the small wheel; then trace the route or distance to be measured with the wheel. The pointer will then indicate on the dial the exact distance measured in proportion to the scale of the map. The pointer will show the exact number of statute miles, nautical miles or kilometers. ø 43 mm, 50 g