2 WIRE internal unit with handset for wall mounted or table-top installation (with specific support to be purchased separately). Keys available: auto-switching on / scrolling, door lock release, staircase lights control and 4 configurable keys only in the A12M model (e.g. Intercom, additional door lock activation, generic activations). LEDs used for: call exclusion, door status, connection with the entrance panel. Bell volume adjustment (with call exclusion) using the appropriate selector. 16 different ringtones available For wall mounted installation, the bracket supplied must be used.