Who wants to sleep peacefully, should better stay away from Merten smoke detector. Have this model returned since 2011 and after a few weeks because of false alarms. The new have disturbed our sleep after a few days. Despite several attempts to set other Frquenzen there were repeated false alarms. Now there are the expensive smoke detector for a long time in a drawer, where they no longer tear us from sleep. Will buy other, certainly not by this company !!!!
