We carry a wide range of 110 Volt - 220 Volt Step up/down voltage converter transformers. A Voltage transformer is used to change the electrical output of a power source, that is, to Convert 110 volt to 220/240V OR convert 220/240V to 110/120V. In the USA, the standard power is 110 volt. A "Step Up transformer" is needed when you want to use an appliance that is 220 volt in USA. A "Step Down Transformer" is needed when you want to use a 110V appliance in a 220V Country. Our Step Up/Down transformers are reversible and can be used worldwide with 50Hz and 60 Hz. Also called power converters, most of our step up and step down transformers come with Universal outlets that can accept plugs from most foreign countries.