Zone Alarms UL® Listed Standard sizes are10" w by 8.75" h and 10" w by 4.5" h. Larger units mount in custom back boxes and the smaller mount into standard 5 gang electrical boxes. Numbers of zones monitored range from 1 - 40 and may have one or two LED indicators per zone. Typical units have an audible alarm which is either board mounted or mounted through the panel. Lamp test feature is available. Red, green, yellow LED indicators are standard. Amber and blue are available, also.