The power supply or internal transformer is rated for the appropriate country. For the models using a digital clock (such as SongBook), the clock uses a 24 hour format rather than the 12 hour format used in the U.S. For models using a digital tuner (such as SongBook), the tuner de-emphasis is set for the appropriate country it's to be used in. Lastly, all models must meet whatever safety and environmental standards are required by each country.