Easy to Use You just need to place the mini metal wheel on the map and roll it, the pointer will show the accurate scale. Convenient Measurement A map measuring gauge can also help you quickly calculate the distance by measuring the distance between two points on the map. Convenient and Fast The measuring distance is convenient and fast, which can measure the actual distance of the curved route on the map. Best Tool It is a great choice for outdoor uses, camping, hiking, cycling, hunting, etc. Material Made of high quality metal and plastic shell, the map measurer is sturdy, wear-resistant, rain-proof and durable. How to use the measuring instrument: When the wheel rolls between two points on the map, the distance measuring pointer rotates accordingly, record the value according to the corresponding scale and multiply it by the scale factor to obtain the actual distance between the two points, which is more accurate than the straight-line distance measured with a ruler. Many map rangefinders are convenient and quick to measure kilometer distances and are designed to measure actual distances on curved routes on a map. Precautions: 1. Use in a horizontal state to ensure accuracy as much as possible; 2. In order to avoid confusion of the magnetic needle, please keep a certain distance from barbed wire and magnetic objects when using it. 3. Do not hit objects with a surveying ruler, so as not to affect the measurement accuracy. 4. The disc surface and lens should be kept clean, do not wipe with a cloth or dirty hands; 5. It should be closed when not in use and placed away from ferromagnetic substances to prevent loss of magnetism. Quantity delivered: 2 pieces. becomeveryrich