Plug Power Meter Energy Electricity Usage Monitor Energy Cost Monitor Watt Voltage Amps Meter Multi Tester, Control and Reduce Your Energy Costs Measures power, energy, volts, amps, hertz, power factor, maximum power, time, days kWh Large, clear LCD display for easy reading Electricity price setting by pressing COST, FUNCTION, UP, DOWN button according to the instructions Built-in Battery(3.6VLow power consumption rechargeable batteries ) backup Displays volts, amps and wattage accurate to 3%