We have three pieces of Merten detectors installed in the house. The detectors from Merten look really very smart and make a high-quality impression. That was it but also already know what there is positive to report it. After delivery I complaining equal to a detector, which had tens of false alarms within the first day. This was replaced by the seller without hesitation. The replacement device then was once calm. But now I have the occasional false alarm again. Sometimes in the evening, sometimes even at night. I have a letter attached to the company Merten - but received no response to date. This smoke detector I can not really recommend. I'll probably therefore replace the detector Merten in the next few days to a more reliable product. Too bad.