at first i went to an area where I got 2 bars and got a little but hyphy and installed 4 on my cell at once, and then i did not get any signal! then i took 3 off so I had the one next to the antenna like they said, it did not really make that much of a difference, although it seemed to keep the bar slightly longer, but the one thing that made this product worth while to me was the fact that it reduced gsm noise (people with gsm phones ( cingular , tmobile) probably have heard this noise, it interferes with speakers that you are next to it makes a modem noise esp when you are getting a call) but this completely reduced this noise, so it is good for something