Excelvan LCD Display Smart Plug Power Meter Energy Watt Voltage Amps Meter with Electricity Usage Monitor Reduce Your Energy Costs WARRANTY: One year warranty, 100% satisfaction and zero hassle returns guaranteed. PLEASE NOTE: For safety concern, please make sure the pressure and current usage range (Operating voltage should be lower than 120VAC; Frequency display should be lower than 60HZ; Operating current Max is 15A.). Please also make sure the house electric equipment has no short circuit, overload and wiring aging conditions to make sure the safety use. CALCULATE: Electricity expense. Electricity price setting by pressing COST, FUNCTION, UP and DOWN button in according with instruction. MEASURE: Power(W), energy (kWh), volts, amps, hertz, power factor and max power(W), time, days - kWh is vital as this is what your electricity bills are based on! Large, clear LCD display for easy reading (screen dimension: 45mm x 70mm). Cumulative Kilowatt-Hour Monitor. DISPLAY: Set electricity price value which ranges 00.00~99.99COST/KWH. Display volts, amps and wattage accurate to 3%. Low power consumption. Built-in battery(3.6V rechargeable batteries) backup, allow meter to be moved and viewed without losing readings.