10 In 1 Multi Function Outdoor Survival Military Camping Hiking Compass Tool Kit Combination Compass Kit|Compass "1. Thermometer: Measure the ambient temperature. (-20-60 C) 2. Hygrometer: Measure the relative humidity of the environment. 3. LED lights: convenient for you to use at night. Replace the battery: (1) remove the magnifying glass and ruler (2) loosen the three screws (3) replace the battery 4.Reflector: Ask for help in the countryside, reflect the sun, and send a bright signal. 5. Spirit level: determine the level condition 6. Compass: Measurement of magnetic azimuth (the relative function of the compass to acquire data at the horizontal and vertical levels.) 7. Whistle: Call for help in the countryside, send a signal, (use the tappet to push the whistle from the third hole on the left) 8.Magnifier: Find a coordinate on the map. 9.Ruler: Measuring distance. "