By simply entering the unit cost of your electricity and plugging an appliance or extension lead into the power monitor, the LCD screen enables you to easily see the cost of the plugged in appliances. It allows you to see useful data such as: cost generated by a socket, tariff, power factor, kilowatt hours used (as found on your electricity bill), active watts consumed, apparent power, voltage from the socket, amps used and frequency of the electricity (mains power is normally 50Hz).