Possession of the smoke detector is now about 1 year. Looks not bad and is indeed of ABUS ..... The insertion on the base plate is a bit fiddly but creating quite (also on a swivel chair standing). Moreover, one need only turn all 3years (lt. Advertising at the hardware store) to change the battery. After 3 months, however, the first battery was empty. OK - can happen even once. New and used goods. After 12 weeks, the same game. So let the 20 Pack Varta ordered industrial blocks. The hold 10 weeks +/- 5 days ago. These maintenance intervals now also disrupts the frimelige attachment and also the extremely tight sitting battery clip. In the swivel chair I renounce now, because I do not even want to put on the nut because the stupid part. So anyone who would like to deal with in his spare time with electronic waste and not put the puzzle about 25 maintenance costs per year, which is the part to know about. If it has power because it works so well. Everyone else I recommend an affordable device from discounters that will save nerves and money.