Advantages:
- Gong needs no battery because it is plugged directly into the inner socket (battery is outside only for the doorbell plate required)
- Volume absolutely fine
- Goes through walls, where, for example, fails my phone
- Following circuits possible: only Gong - Gong with signal light - only signal light
Disadvantages:
- No Laustärkenregelung
- No different melodies adjustable
Important Note:
This part can not be plugged into an external power outlet with hinged lid, since the connector poles sit too far down and the cover (the cover!) Can be opened with most Außensteckdose only up to an angle of 45 degrees; The gong is thus great for an outside outlet with hinged cover dimensioned. For sockets without lid (for example in the interior of a house), no problem!
As regards the volume, I can only say that this is absolutely ok -I case anyway almost out of bed when I sleep and the gong sounds (and I have a good sleep!). When pressed once the bell sounds the way 2x a simple double Gong; thus is the bell not to be missed.
If you can live with the above described "disadvantages", is very well served with this bell.