1. Digital multimeter: This power meter can measure and display voltage, current, active power, frequency and power factor at the same time.Use a shunt transformer for easier installation. 4. One-click control: buttons can be used to control backlight, reset , and preset power alarm limits 2. Overload alarm function: When the preset value exceeds the preset value, the backlight and power supply flash at the same time, and an alarm be emitted.You can preset your own power limit 3. Automatic data storage function: When the power supply is suddenly lost, the last be automatically stored.No need to worry about data loss caused by sudden power outages. 5. LCD display: Large-screen LCD display, full line of sight 180°, blue backlight can be manually turned on/off.PZEM-022 requires an external power supply to light up the screen, Weight: 0.64815905028 pounds, Manufacturer: Awwertse