I have 2 TVs, one in the dining room, the other in a room. They share the same building's roof antenna, so start from the same branch into a wall. Since installing the new DTT channels, and will know why ... several channels were not available on the second TV (D8, 14, 15, 16, 17 and 18), while on the main TV no problem. Before these chains exhibited displays bugs, freezes, etc. Since the addition of new channels, no reception, bluntly. So I thought to a receiving power problem that the second TV or remote (extension of several meters).
So I bought this small amplifier box without really believing in it. Considering the price I told myself that I did not risk much (though). Scare initially because during the first installation I plugged directly behind the second TV. Result: no effect at all. So I plugged the bousin immediately off of the main antenna behind the first TV, and there miracle: everything works! I found all the channels on the second TV (of course after a new scan) and they work without problems! I turned fully small knob on the case, I do not know if it's useful.
Conclusion: good product that does the job asked. :)