Easy to install and test. Very good sound level. Quality English, in addition recommended by the British brigade. Warranty and battery life of 10 years. Excellent price / quality ratio. Thickness well below that of its competitors. Contrary to one of the comments, I think it is a rather environmentally friendly product, compared to standard products for which it will use 10 batteries for the same duration of use. The manual exists in French / German, but not easy to find, linked: [...]