This is one of many devices on the market. Its likely a big capacitor, and it probably does improve your power factor, but most of the claims are bogus. I've even seen news stations have positive reviews, mostly by the clueless reporters.
Residential users aren't charged for power factor. Your bills are all in KWHs, which means that the electric company does the PF conversion for you. You won't save anything on your electric bill. You might get slightly better engine life on your fans, but there's no way to measure the benefits.
And, if that's not enough information, this is: I called one of the other company's 800# at 4am on a Sunday. Someone answered and provided a sales pitch. That essentially was "proof" in my mind that their claims were bogus.
http://energyexperts.org/energy_solutions/...§or=All