The set provides you with three smoke detectors HSRM11010 at a preferential price. The photoelectric ABUS smoke detector reacts to smoke particles. If too much smoke enters its measuring chamber, a loud alarm signal is triggered. The smoke detector is mounted at the ceiling in the center of a room. The minimum distance to the walls should be 15 cm, the distance to the corners at least 50 cm. The operation range of the smoke detector is up to 40 m². We recommend installing one smoke detector each in the hall, the stairways, living room, and bedrooms. In the event of fire, the integrated powerful piezo sounder provides an effective alarming – at a minimum sound level of 85 dB. Included in the scope of delivery is a high-quality 9 V Lithium battery. The battery lifetime varies depending on how often you run the detector's function test. This is done easily by pressing the function test button. It is recommended to carry out the test once a week. The detector registers low battery and then issues regular beep tones. The home smoke detector is VdS approved. This guarantees high safety.