Looking for some peace and quiet in that home theater? Happen to have a massage room or yoga room in the home? You might be looking for this. The Cell Phone Signal Jammer simply blocks signals to cell phones within 30 feet. While we’ve heard of it being used on morning commute trains, libraries and restaurants - we presume private use is likely best. Blocks GSM signals 850, 900, 1800, and 1900 MHz, but doesn’t block 3G - for that you’ll need this one which comes in a long range and short range model. Comes with battery adaptor, though unit is self contained. You can relax now. $166.