With these Battery to Electric Converters you can switch out a battery operated movement for an electric movement just by taking out the battery! The conversion is achieved by BACK-UP's patent pending external AC-DC power supply, which will simultaneously operate the clock and trickle charge its internal Ni-Cad battery. BACK-UP insures the clock continues to function in the event of a power failure; essentially making it an Uninterrupted Power Supply (UPS) for the clock.