The Alpha Communications/Golmar FA-GB2/B power supply is used exclusively with the GB2 series systems. The FA-GB2/B power supply is located between the entry panel's BUS and the monitor's BUS. The capacity of the FA-GB2/B is currently up to 32 monitors and one (1) entry panel. If there is more than one (1) entry panel, then the DP-GB2A needs to be installed. For systems larger than 32 monitors, you will need additional FA-GB2/B power supplies and the required RD-GB2/A repeater/router unit(s) as needed. The FA-GB2/B has a relay built-in for the connection of the staircase light. This relay is controlled from the monitors.