1. Press the power switch (8), and when you hear a "click" or vibration, it means that the power has been connected and the green light is on. If there is no sound or vibration, the battery is not installed or the battery is not making good contact. If the alarm continues, it means that the battery can no longer be used and should be replaced. 2. High-sensitivity detection can be performed after the sound stops after starting up. Hold the handle to scan the detection surface around the object to be measured. When there is a metal object, an alarm will sound. At the same time, the green light turns into a red light; stop scanning, the alarm stops, and the red light turns into a green light. 3. Low-sensitivity test: To remove small objects from metal objects, press and hold the low-sensitivity switch (3). When scanning around the object under test, an alarm will sound when there is a metal object. At the same time, the green light turns into a red light; stop scanning, the alarm stops, and the red light turns into a green light. Because the sensitivity is reduced by more than 5 times, the detected metal objects are generally relatively large.