The installation is really easy. Especially if you live in an old house for rent, which is not always a reliable screw holds and you also do not want to pierce the ceiling, this magnetic attachment is a great thing. I have installed a new smoke alarm and did not want to drill. So I, as described in the instructions, the metal plate glued to the ceiling and well-pressed for 10 sec. Then I glued the plate with the magnet on the base plate of the smoke alarm (GEV FMR 4023) and then just hung under the ceiling. The smoke detector can be removed at any time, eg. As for battery replacement as including base plate. Keeps better as the Tesa-Power Strip solution.
However, this type of mounting works only when the back of the smoke detector mounting plate is flat and has at least as 2 cm² adhesive surface. The metal plate, which is glued to the ceiling can be painted over.