I set my phone down on my computer desk for 10 minutes and I checked the Signal Strength on my Droid X and it read -87 dBm. After putting the Universal Cell Phone Antenna Booster on the inside of my batter cover I set my phone in the exact same spot for 10 minutes and It read -83 dBm (closer the number to zero the better the reception). So I guess it works a little bit. Check out the picture I posted of the signal strength before and after.