The AARC-EVAC™ ARX50 Standalone Wireless Linked Emergency Alert
Siren & Message Broadcast Units, incorporates an in-built Battery
Backup UPS. They are fully self-contained making them ideal for use in
locations where there is no existing PA system, or to cover areas not
serviced by a PA system or as a full standalone network of units to
provide for redundancy if the PA system fails for any reason.