SCAM!
SCAM!
SCAM!
The internet is full of ads for these ruddy devices, under lots of different brand names. (Some of those ads even appear here on AB. Grrr!). They are all FAKE!
Don't just take my word for it. Search YouTube for 'power saver scam', look for similar terms on the MoneySaving Expert website or get a physicist to check out the maths here:
http://electronicsbeliever.com/electricity-saving-box-scam-revealed/
If such devices actually worked, every builder of new homes would be including them in their electrical circuits as standard. They don't, simply because they DON'T work!
DO NOT BUY!