The electronic signal insert has 3 button inputs that you can assign different melodies to. With a connected button, you can call up the melody of the associated button input and also select a new melody. There are 5 different melodies available. Use buttons with a normally open contact or buttons with an orientation light to control the button inputs. Suitable for installation in a 60 mm installation box. Without claws, for screw fastening. Nominal voltage: 8-12 V AC. To be completed with: Central plate for acoustic signaling device system M 3520.., MEG4450-03.. /-04..