Color: Army Green Product size: length 9.7CM diameter 2.8CM Weight: 50 grams Material: ABS high-strength anti-drop and high-temperature engineering material Functions: Survival whistle, compass, thermometer, signal mirror, magnifying glass, flashlight, sealed compartment   [Battery replacement method] Take the thing apart, look inside the mirror part in the middle, it is behind the LED light, there is a screw, that is the place to change the button battery. Specifications: 1. Standard high decibel survival whistle 2. North (South) needle (accurate and clear at a glance) 3. Thermometer (The first time to grasp the current temperature) 4. Survival reflective signal mirror (The person who uses the principle of sunlight reflection to search and will explain his current location) 5. Tinder magnifying glass (In the absence of fire in the wild, the principle of focusing sunlight on a magnifying glass can be used to refract sunlight to withered grass and leaves to generate fire, which is better than "drilling wood to make fire" ~~ Ha ha ~~) 6. White LED flashlight (Under the premise that there is no light in the wild, the life of the lighting system and LED bulbs for emergency use is 10,000 hours) 7. Sealed warehouse (You can put your own lifeguard in it before you travel: write your name, address, phone number, blood type, etc. so that the rescuers can grasp your situation in the first time) 8. Nylon lanyard (It is more convenient to carry around) Package Included: 1* Survival whistle