Sinthesi S2 4-button module for telephone outdoor station

4-key expansion module to be connected to telephone outdoor stations item no. 1148/1 or item no. 1148/2 or to a previous expansion module item no. 1148/4 (via supplied cable) for a maximum of 64 keys. Possibility of associating 2 24-digit telephone numbers to each key, to differentiate the destination in day and night modes or for sequential calls to two telephone destinations.