Additional bell button for FD20 / FD25, IP44, with nameplate and confirmation LED. Easy registration on the gong unit of the set. Power supply: 1x 12V MN21/23A alkaline battery (included). Easy installation with adhesive pad or screws (both included). Radio range up to 200m (outdoors). Dimensions: 34 x 88 x 20mm. Up to 8 bell buttons / motion detectors can be registered on a gong unit, with individual melodies for easy call differentiation. The number of gong units per bell button / motion detector is not limited, but note the radio range.