probably effective but can only fit US plugs
It is probably effective, but the down side is I ordered it from Singapore.  The product info didn't warn me about the plug - it couldn't fit our wall power points, and even after I used an adaptor, both (I ordered 3 and opened 2) blew and can't be used anymore.  Totally a waste of money for me.  My advice is if you aren't from the US, forget about ordering this.  I should have just spent the money and bought the more expensive ones (but international brands) sold here cos once you add up shipping charges, the costs were almost comparative.
Rating: 2 stars