No kidding!!!
Just wanted to update and let you know I finally got around to fitting one of these and they really are excellent
This isolated my bad house wiring allowing direct adsl connection to the engineers socket (behind master faceplate) and my speeds went from about 1.2mbit to 4mbit which is the max I can expect given the distance from the exchange. I've never had such as fast and STABLE connection... I used to drop and resync multiple times per day and now I'm permanently connected with no drops or resyncs.
These are the genuine BT article and remove the need for any further adsl filters. They even have connectors on the backplate to run an adsl extension from the master socket.
Very highly recommended