Protect household appliances: built in quality lcd digital display with blue back light, this voltage monitor is convenient for you to view the data on it even in night, this test can immediately detect and measure the current voltage by connecting to the switch plug or the other kind of wall socket, it allows you to check on power health of devices for preventing the low voltage damage to your household appliances<br> Wide measuring range and low consumption: measuring range: ac 80 - 300V, consume power: less than 1W (about every 1200 hours consume 1 kilowatt-hour), 2 prongs flat us plug with compact size design is ideally applicable to measuring the ac voltage in family, office space, industrial and mining enterprises, etc.<br> Adjustable potentiometer: there's an interior potentiometer for accuracy adjustment. just use screwdriver to open the outer coving and adjust the potentiometer with small size screw driver, adjust potentiometer in counter-clockwise when its excessive voltage, but if display voltage is too low, adjust potentiometer in clockwise<br> Versatile feature: this volt meter is for more than just measuring voltage, with its soft blue back light feature, it can be also applied as a light for night and a simple electrical test pen, while enabling you to view the data even in dim atmosphere<br> Wide applications: it is ideally applicable to measuring the AC voltage in family, office space, industrial and mining enterprises, etc.; Please keep the children away from the product and do not use the product in a damp environment