The U55BHAA104-WEB is designed to work with multiple master clocks and correction signals. This unit is programmed to identify the signal it receives from the master and operate as that style of clock. Changing clock operation from one style to another is as easy as unplugging the clock from one system and plugging it into another. If needed, changing the placement of 2 small jumpers on the circuit board can change the voltage required to run this clock from 120vac to 24vac or 24vac to 120vac. This clock provides 15 minutes of backup run power without the use of batteries.