I think the smoke detector visually very successful. They are functional and have a clearly audible acoustic warning signal. Only the ceiling mount using the supplied screws designed to be difficult, because they are far too short (only about 3 threads engage in the dowels and rotate therefore easily), I took a little longer screws and now they keep 1a! Have products never done with Mertens generally bad experiences, because my whole switch and socket range by Mertens are.
