The monitor can be widely applied in AC 80-300V mains measurement, such as office, factory, laboratory, household and so on. You can use this item in RV as a way to view voltage to prevent issues with appliances.You can use this item to monitor the voltage of other appliances; when this volt gauge displays too high or too low voltage, you can selectively turn off your appliances or equipment so as to prolong the life of your appliances.Available Range: Widely applied in AC80-300V mains measurement.It enables you to plug in RV to monitor voltage for preventing issues with appliancesIt's a must to let the children from the product. Do avoid using the product in a damp environment.Potentiometer Adjusting : Just use screwdriver to open the outer coving, then adjust the potentiometer with small size screwdriver. Adjust potentiometer in counter-clockwise when it's excessive voltage, but if display voltage is too low, adjust potentiometer in clockwise.Measuring accuracy: +/-1.5, +/- 2 wordMeasuring range: AC 80 - 300V (110V, 220V)Consume power: less than 1W (about every 1200 hours consume 1 kilowatt-hour)Number of digits: 3 digitsPotentiometer adjusting :Please use the screwdriver to open the outer case of the voltmeter.Then adjust the potentiometer with small size screwdriver.If the displayed voltage is too high, please adjust potentiometer counter-clockwise.If the displayed voltage is too low, please adjust potentiometer clockwise.Plug Type:EU Plug,it applies to Indonesia, Germany, France, , Italy and so onMaterial:ABScolour:WhitePackage Contents:3 x Voltage test metersOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.