At ESW Supply we stock or can make a custom wording signs.   The custom signs are constructed with a white or black thermoplastic housing.  They come standard with a universal mounting bracket for all mounting positions and a directional arrows.   A 90 minute Nicad battery is included.  Dual voltage 120/277. Green Led and black housing will have a 7-10 day lead time.   The most popular signs are X Ray in Use, Area of Rescue Assistance and MRI Magnet Always On