I brought an Efergy Elite Wireless Energy Saving Monitor because I have become concerned with the cost of my energy from my supplier. The meter does exactly as is described and I took a meter reading then attached the wireless monitor receiver to the cable in the meter box, then I could get a reading of my energy usage via the display box and compare this with the meter. I have been checking this regularly as my supplier just bills on estimates, based on no fact and that they are constantly over charging me. Judging from both meter readings and from my tariff I am being overcharged. The efergy meter has alerted me to the costs of using
certain products and gives a you a good history of what you have been using and has helped me be more energy efficient. I found a handy little thing it does - you can set an alarm to go off if your usage goes over a marker which you can set i.e 5kwh. I would advise that you monitor what your readings are for the 1st few weeks then set this as a marker, this will help you cut your energy costs by using it as a bench mark to try not to go over and again keep adjusting it over time. It a good product with lots of options, I brought it online from a shop see link http://shop.energyconnectuk.com/ it was about £40, the product came quickly and I would recommend it to others.