For the early detection of smoldering fires and open fires with smoke development indoors according to the photo-optical measuring principle (Tyndall). Suitable for connection to external systems such as Busch-free@home® via the Busch smoke alarm RF radio module in combination with the Busch-free@home® alarm stick. Permanently installed lithium battery with a service life of at least 10 years. VdS certification Tested according to DIN EN 14604. Acoustic alarm with 85 dB at 3 m. Dismantling protection. Up to 20 detectors can be networked via 2-wire cable. Up to 20 detectors can be networked via radio module 6828. >Q< certificate in accordance with VdS 3131 / vfdb guideline 14-01. Diameter: 120 mm. Height: 47.50 mm. Power supply: 3 V lithium battery (permanently installed) with a service life of at least 10 years.