Power saving electricity energy saver box : Do they work ?

Those Power electricity energy saver boxes you see on Ebay or Amazon.
Do they work ? In my case, NO. It increases consumption by about 40-50 watts !!!
How do I know ? I used an OWL Micro Wireless Electricity Monitor to watch the wattage when I plugged the 'saver' into a plug unit.

I bought one of these 'energy saver boxes' that are supposed to have circuitry that can save perhaps 10% of electricity use in a household due to doing something to the 'power factor' or something. The box is usually sold on Ebay or Amazon as a 'Power electricity energy saving box' or a variation around that term.

The simple way to see if they work is to buy an electricity monitor reader of some sort (I'm using an OWL Micro Wireless Electricity Monitor) then you can view your watt reading all the time. I bought my 'saver box' first and confidently thought I was saving electricity energy and when no electricity was being used it would be zero watts. Then I bought the monitor and found out I was using 40-50 watts all the time until I unplugged the saver ! (that's like 0.96 kw to 1.2 kw a day)

My advice : Every house should have an electricity monitor or smart meter (wireless or otherwise) of some sort so you can see what is going on. Possibly wireless is ideal because you can put it anywhere (such as next to you while you watch TV). And don't buy a power electricity energy saver box until someone can give a good reason !

Amazon USA :
search : 'electricity energy monitor' , search : 'electricity energy monitor wireless'

Amazon UK :
search : 'electricity energy monitor' , search :  'electricity energy monitor wireless'

Note : I am using the OWL Micro Wireless Electricity Monitor but I see now there are newer 'OWL' versions and cheaper alternatives and even the Belkin one that is very cheap may do ok. I will do a video and post about my wireless monitor later. You have a device and a clip around your electricity meter power cord to measure the use (it's easier than it sounds). Then the other part is the wireless monitor which I would suggest should be very portable.

More about the 'power saver box'
For the record here are more details of the 'power saver box'
Mine came as a '2 pin' plug. I had to use a '3 pin' adapter
Specs (for my model) :
Model SD-001
Rated voltage :90v-250v
Rated frequency : 50hz-60hz
Useful load : 15000w (no ordinary house will use this much ?)