This trap is especially useful for those with nearby FM transmitters. The high signal strength can swamp your tuner causing you to loose stations completely on a digital tuner. For analog it causes the signal to bleed over on to the other channels. It causes all sorts of interference that shows up as a herring bone pattern or other distortion. Sometimes the FM audio even comes over the channel. This signal trap reduces the FM signals to eliminate these problems, but it can actually reduce signal on VHF channel 6.