This is a very helpful device to learn what and when you are consuming electric power. You can see the immediate impact of turning on or off any appliance. And the reality of when you think things are off, they continue to consume power. The display shows Kw being used now, as well as Kwh yesterday, in the last 7 days, and in the last month. You can set your $/Kwh and the display will give a daily and monthly value of what is currently being consumed. It does not calculate your electric bill.
The most difficult part of the installation is placing the sensors around the incoming power lines in the main breaker box. This is in the area before the breakers, and cannot be powered off. So you have to be careful where you place your fingers.
There is an option for recording up to nine individual appliance sensors. They are offered in package qty of 1 or 3. I'm not yet sure if this option will be needed.
I would recommend this monitor to friends, and expect it will help to change habits that leave lights and appliances on when they are not being used.