Current exit alarm ALK released in November 2010 does ship standard with an EI (external inhibit) option. ALK shipped prior to this would only have EI if ordered as a Special option.
The Von Duprin exit alarm ALK draws about .25 amp.
PS902 power supply powers up to 8 exit alarm ALK.
PS904/914 powers up to 16 exit alarm ALK.
PS906 powers up to 24 exit alarm ALK.