There are up-to 64 Notification Appliance Circuits (NAC), networked, stand alone or interfacing with the Sync module.
Alarm Sync Module FireWatcher 951
The Sync Module FW951 is a device designed to be used with FW962/FW971/FW981 Horn and/or Strobes with a built-in synchronization circuit to synchronize multiple FW961 Horn Strobes in a complete fire alarm system.