The handling is probably no serious problems: Per test button the rather loud beep you can even listen in advance and then hope that you will then never hear him again, because hopefully it will come at a fire. Another useful feature is that a small light flashes per minute on the unit approximately 1-2x and so signaled its ongoing commitment functioning. In relelvant the batteries lose power, it makes visually and audibly also noticeable and asks for substitution. Before that happens, should pass 10 years according to the manufacturer but, so you have after installation really once a while his calm and just feel safer while sleeping.
