This was the first question we had as well! In 1836, Michael Faraday created a cage with zero frequencies going in or out, and they named it a Faraday cage. Our Faraday Bag, or static silver bag, is 7mm military grade. It is not an iron-clad cage, so signals and frequencies still go in and out of it. There is an incredible discovery we made.There is a Physics component where the good or negative ionic charge of the crystals shows through, and the bad or positive, polarizing charge of a cell phone quieted to safe levels. All the tests we have completed show that having the crystals inside the static bag amplifies their resonance. The static bag helps double seal the crystals to preserve their properties. It also keeps them from needing to be re-ground very often.