Aiphone NEM-10A-LD 10-Call Master w/Handset for Long Distance

10-Call Handset Master for Long Distance/Elevators is designed for communication with remote locations up to 4000' away, or to each elevator in a building.
Features:
10-call master with handset Two-way communication between master and subs Clear communication to subs in elevators Substations can be up to 4000' away Call-in from sub remains lit on master until answered Hands free communication at sub stations Sub stations are weather resistant Common applications include office complexes, large commercial facilities, gated entries, parking lots and airports Sub stations are available in surface or flush mount styles require a separate circuit board to be added for the call-in function Three wires are required to each sub station