CO alarm has a latching alarm feature. The unit latches or remembers which alarm initiated the event. The latching alarm feature will remain active until you press the test/silence button. This makes troubleshooting the jobsite quick and easy. Just look for the alarm with the latching alarm indication. Clean, reposition or replace the initiating alarm if necessary. There is no need to waste your time and effort replacing the other alarms. Also, BRK alarms feature a low battery latch that is activated when the alarm is in the low battery condition. Similar to latching alarm feature, a light will be blinking on the alarm with a low battery.