Conclusion after 3 months. Works

Thanks to the manual in one of the reviews (thank you!) I could teach my 2 piece, the enclosed manual was totally wrong.
Cheap smoke detectors that work there are many, many produce after a while but frequent false alarms, like at night, what is "unpleasant". These have not yet made the date (3 months).
The senseless instructions I would normally, more depreciate with networked smoke detectors where one has to rely on a manual, given the low price I draw from only one star.