Keep your electric bills at bay with the Kill-A-Watt Electricity Usage Monitor. Cut down your costs and find out which machines are actually worth keeping plugged in. Simply connect your appliances to the monitor and it will assess how efficient they really are. The unit's large LED display counts consumption by the kilowatt hour, the same as your local utility. You can calculate your electrical expenses by the day, week, month, or year while also checking the quality of your power by monitoring voltage, line frequency, and power factor.