The Franzus FR22 converts 120-volt domestic electricity to 240 volts, so that most foreign appliances rated 0-50 watts can be used with the USA's power supply. Continuous use upon 0-30 watt appliances is acceptable, and intermittent use on appliances rated from 31-50 watts is permitted. The female receptacle upon the FR22 is the standard ungrounded 2-prong unit of Europe; devices designed for other overseas power supplies can be used only with an adapter converting them to the European 2-prong standard.