High sensitivity of voltage monitoring, monitoring input voltage range: AC175V-AC265V. If you use it in places where it rains, place the sensor at a specific place. If there is a drop of water on the sensor, it will give an alarm, but at the same time, it should be noted that the main part cannot rain, because the main part is not waterproof. " Alarm volume up to 120dB or more; can use ordinary batteries DC9V, but also rechargeable batteries. The product does not charge the battery. Widely used in telecommunication rooms, hospitals, farms, industrial and mining enterprises, refrigerator institutions, substations, etc. As a power failure alert, the failure of current reminds the product. Product How to install the battery in the product The product needs to purchase a DC9V (6F22) battery for the installation. Amazon sells this battery ASIN: B003PAMIQG Product power supply: 6F22 9V battery (not included in this product, you need to configure your own battery) DC9V battery positive and negative contact spring heads are inside the product, pay attention to the positive and negative directions when installing. Can be turned off manually. ent when the product triggers an alarm The product power jack is used to connect the power state to be detected (monitoring voltage: AC85v-265v, 50~60Hz), and it will trigger an alarm when there is no voltage. When an alarm occurs, the switch on the device can be turned off manually. The product does not consume power from the connected source socket. Thus, the device does not consume AC power. When the alarm time is longer, the more DC9V battery power is consumed. When the alarm sound becomes smaller or the alarm sound is discontinuous, the DC9V battery should be replaced. When the number of alarms is very low, it is recommended to check battery power once every 6 months and replacing the single DC9V battery (6F22) once a year. Product size Product plug cord length : 100cm/39in Product size: length 5.5cm/2.1in * width 2.5cm/0.98in * height 10cm/3.9in The product has a wide range of usage scenarios Widely used in telecommunications rooms, hospitals, farms, industrial and mining enterprises, institutions, substations , etc. As a power failure warning, a power failure alert product. For example, frozen food or medicine in the refrigerator can be detected in time due to power failure sudden power failure to prevent damage. For example, the mechanical equipment or experimental computer in the laboratory can be detected in time due to a sudden power failure during the experiment to prevent damage. losses. It can be used in conjunction with other alarm monitoring systems. When criminals attempt to cut off the power supply (causing the monitoring or alarm system to fail), the alarm will sound immediately at a high level Under normal power conditions If there is a sudden power failure (power failure or tripping), the alarm will be triggered immediately. (End alarm can be disabled,) the alarm will end immediately after the power supply is restored, and the alarm conversion time: 0.5 seconds