I bought the ring for the garden. Transmitter and receiver are protected. Even when you try if it works at all, we had to make other arrangements. Transmitter and receiver are max. 20 meters apart, apparently interferes 1 small bush between. In the apartment there works fine, but I do not need a second bell. From because of 100 meters. Even without obstacles does the thing like a remote control, when the batteries are all: one presses and presses and nothing happens. Conclusion 1 day: at distances greater than 10 m absolute rubbish!
