This smoke detector has obtained the safety certificate from the German quality institute TÜV and is therefore one of the best-selling smoke detectors in Germany. The SD11 is a high-quality, beautiful and very professional smoke detector with a battery that lasts 10 years. This detector is easy and effortless to install with the supplied screws and plugs. Product specifications Type: Standalone (not connectable) Battery: 10 years (sealed) Sensor type: Optical Alarm level: > 85 dB Safety standard: EN 14604 Mounting: Base plate with screws Diameter: Ø 120 mm Height: 45 mm Where do you place a smoke detector? At least install smoke detectors in the hall and on the landing. This is usually the escape route if a fire breaks out. It is even better to also install detectors in all bedrooms and the living room. And if you want maximum security, install detectors in all rooms where fire could occur. In any case: - on every floor against the ceiling - at least 50 cm from a wall or corner and not in a draft or near mechanical ventilation - in the room where the bedrooms open (escape route)