The AARC-EVAC™ ARX50-R Standalone Wireless Linked Emergency
Alert Siren & Message Broadcast Units, incorporates an in-built Battery
Backup UPS and a Repeater Transmitter. 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.