The device makes a great impression, was taken very quickly into operation, also has the first test survived (a Hells noise). Now the good piece hanging from the ceiling and makes hopefully what he intended. Actually, it's like any good insurance - costs money - brings no added value - and is doing what it should, when things come to disaster. I could have done without it, but it should be mandatory. That must now decide for themselves whether the money is invested properly. What I like is the long battery life.