The AARC-EVAC™ ARX52, ARX53 & ARX54 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.