User blog comment:Master Sima Yi/Assassinews 02-08-'12 — Official AnvilNext Trailer/@comment-124.189.1.42-20120806070733/@comment-4043223-20120809111906

Ahh, I see you wish to know more. Well it depends on the foil type and the average proximity to an Apple or sometimes an iPad...

Ultimately, the shielding effectiveness of foil depends upon the type of incident field (electric, magnetic, or plane wave) it is subjected to, the thickness of the foil, and the frequency (which determines the skin depth). Shielding effectiveness is usually broken down into a reflection loss (the energy bounces off the shield rather than penetrates it) and an absorption loss (the energy is dissipated within the shield).

Studies have shown it works 60% of the time everytime in deterring foreign signals and women.