In message , "Dave Plowman (News)" writes
A couple of years ago I got one from B&Q for an elderly relative who is going a bit deaf. The one button operated two sounder units, one plugged into the mains, the other battery operated, so they could be located in different rooms. This seemed a good arrangement, and both sounders were quite loud. I didn't find the distance to be a problem, but it's a smallish bungalow.
Unfortunately the reliability turned out to be extremely poor: at times the darned thing would sound when nobody pressed the bell-push; even worse at random intervals of a few weeks one or both sounder units would stop working, until I next visited and could reset the whole thing by removing all batteries/mains power and setting up from scratch again.
I've now removed all these wireless units and replaced with a couple chime units powered by mains (via a transformer) and all hard-wired.
The one I had the misfortune to buy was by Friedland and marked D422 Doorchime kit. I strongly recommend not buying this, and from what I have heard since would suggest avoiding all units marketed by Friedland.