Hi Jay, Hi Jarrod,
Boy, how stupid can some people get. Everyone knows that Al foil will behave as an antenna. Thus amplifying the signal whether generated internally or externally. Therefore these helmets are totally ineffective.
It is much better to construct the helmets using fine steel mesh. The attenuative properties are much greater. The signals will be absorbed by the steel.


The governmet is keeping that info very quiet.
I don't believe I am writing this rubbish.
Cheers