Many countries with ties to Europe use 230-volt, 50 Hz AC mains electricity, using a variety of power plugs and sockets. Difficulty arises when moving an electrical device between countries that use different sockets. A passive electric power adapter, sometimes called a travel plug or travel adapter, allows using a plug from one region with a foreign socket. As other countries supply 120-volt, 60 Hz AC, using a travel adapter in a country with a different supply poses a safety hazard if the connected device does not support both input voltages.
