Review on Goldsource STU-500W Voltage Transformer Converter: AC 110V/220V Step-Up/Down Power Converter with 5V USB Output, 500 Watt - Efficient Power Transformation Solution by Mario Beats

The Step-down transformer is just what you need Match any input voltage to any required output. In my case, I am stepping up the voltage from 120VAC in the US to 220V in the UK. Very easy setup, just select the input voltage on the back of the transformer and the universal 220 volt socket on the front will power any 220V AC plug. The only thing to watch out for is to make sure your transformer is rated for more watts than the device you're plugging into it. There is a USB port for charging. I have a 500 watt model that doesn't have enough power for, say, a hair dryer, but powers my guitar amp with no problem. It's a bit heavy for travel, but when you need it, you really need it.