1.4. This machine uses a 9V battery. You can open the back cover to the battery. The product principle diagram is as follows. The red and black meter pen is equivalent to the switch. When not measuring, the circuit is not on and there is no current consumption. A 9V battery can be used for 3 5 years. 2.2. Usage method: Use the meter pen of the machine to contact the two ends of the wire. If the machine issues a sound and light alarm, it means the wire is conductive; otherwise, it is broken. 3.1. This machine is mainly used to dry test the continuity of wires and other conductors, equivalent to the continuity testing function of a multimeter, simple and convenient to use. 4.3. Before the test, directly short circuit the meter pen of the machine. If there is a sound and light alarm, it is normal; if not, please check whether the meter pen or battery is normal.