These are step up/ down transfomers that can convert 110V to 100V or vice versa. These transformers are meant for using japanese products in the USA or for using american products in Japan. TRANSFORMER PURCHASE GUIDE: Remember to leave at least a 100% slack for the transformer. For the TVs, the power surge margin is 5 times the wattage of the TV. Heating appliances, laser printers and power tools spike when you turn them on. For these products you need to buy a transformer that is at least 3 times the items capacity.