With the Elro FS7810 Duopack you immediately have 2 smoke detectors. Each smoke detector has a built-in lithium battery with a lifespan of 10 years. The smoke detectors have a diameter of 7 cm and a height of 3.4 cm. Very compact. When the optical sensor detects smoke or fire, an audible signal sounds 85 dB. Hard enough to not miss the alarm signal.
Test the smoke alarm regularly to make sure it is working properly.