Audio speaker unit for Simplebus system with terminal board and double amplifier, watertight loudspeaker and electret microphone, Both, microphone and loudspeaker volumes, can be adjusted from the front. Complete with microprocessor and DIP SWITCH with 8 positions for programming the calls to the users. 12 V AC power supply (use Art. 1395/A). Electronic door-opening function on board (3A). To be inserted in modules Art. 3320/0, 3320/1 and 3320/2. Dimensions: 102X55X35 mm. From the RI27 it is compatible with all SBTOP functions and products. It allows call addressing for up to 120000 users.