Features: 1) Photoelectric effect 2) This recently developed photoelectric sensor-camber is insensitive to interfering influences 3) Every device is separately calibrated in order to avoid false alarms due to cigarette smoke 4) The power supply is electronically regulated, thereby maintaining a constant sensitivity of the alarm 5) Battery operation 6) The functioning of the detector is maintained even in case of a power failure 7) In an average the battery\'\'s (standard 9V battery) service life is 1 year 8) Signal lamp (LED) 9) A flashing small light (every 43s) signalizes a failure-free operation 10) Fully automatic test function 11) Advanced electronics ensure the best possible operating readiness by means of an automatic self-test function 12) Battery warning function 13) By means of a warning sound repeated every 43 seconds (for up to one month), the smoke detector signalizes that the power supply of the battery is insufficient and it needs to be replaced 14) Control button 15) Temporarily increases the detector\'\'s sensitivity to test the alarm function 16) Noisy (85 dBA) piezoelectric warning sound 17) Vibrant warning sound in case of fire alarm 18) Approved quality 19) Thoroughly tested to guarantee highest reliability and a long service life 20) Produced under rigid quality controls 21) Certified according to the European norm prEN ISO 12239 for single smoke detectors 22) CE and TUV certified security