Busch smoke alarm, ProfessionalLine, studio white, for the early detection of smoldering fires and open fires with smoke development indoorsFixed lithium battery with a lifetime of min.10 years test button and mute function certification, tested to DIN EN 14604stic alarm with 85 dBA to 3 mssembly protection to 20 detectors networked via 2-wire cable to 20 detectors can be networked via the 6828 radio module.Q certificate according to VdS 3131 / vfdb Directive 14-01eter:120 mmht:47.5 mmdalone is noorked via cable is yesorked via radio (optional) is yes.-Primary power supply is a rechargeable batteryage type is DCme is 85 dB (a) baseht is 47.5 mm diameter is 120 mmur is white.-