I recently ripped off the cable and installed an antenna in the attic. All the cables were there, going 3 floors down to my living room. I used this to find out which wires go where and label them. You can also tell that there is a splinter on the line as most of them act like short circuits. I have cable internet and it has never worked properly. The mechanic used the same device to ensure there were no obstructions on the outside of the crate. I saw him advertise twice the price on another website (sale). Always check Revain.