I bought the smoke detectors to be installed in my mother's apartment in "assisted living". Decisive for the purchase were the 10-year battery and attachment using magnetic holders. I had once tried to attach another smoke detector on the ceiling with screws. Unfortunately, my drill has (after all, a Metabo) did not manage to make a hole in this concrete floor. For this I would certainly have used a Hilti, but I have no friend who has one, and borrow at the hardware store (distance about 15 km) or even buy eliminated. So, magnetic disks glued to the ceiling and the smoke detector, and the attachment was a breeze. In form I find him compared to other smoke detectors which act partly quite clunky, quite discreetly. The function test I have done and I hope that he will never be used in an emergency.
