I bought a massager from a US-based website. When I received it it doesn't work at all. Since there was no user manual or anything I contacted the company and they said that you had to use a 220V outlet. That means I need to buy a voltage converter to convert 110V to 220V. It seems like an easy task but turns out to be the opposite. Why? People in America buy 220-110 converter when they travel to Asian, when Asian travel to the US they buy 110-220 converter; therefore, there is not much market for 220-110 converter in America. I didn't realize this until all the electronic stores I visited did not carry such a product. Eventually I resorted to Amazon. It was not easy but I found this one. It works perfectly. I was finally able to use my massager. I recommend this product to anyone who want to step up the voltage.