A method of stirring and apparatus for stirring using electromagnetic stirrer units is provided. The method and apparatus are particularly useful in relation to molten metal stirring. Each stirrer unit is mounted on a moveable carriage so that it can be moved between a first location, a second location and potentially further locations. The same stirrer unit is used to provide stirring at each location, so allowing multiple locations to be stirred but only requiring a single stirrer unit to do so. The method and apparatus also provide convenient connection of air cooling to the stirrer unit.