Seems if you scroll around shopping websites and look at the negative reviews you always see people saying things like “never worked at all” or “stopped working soon after”.
It can’t really be that involved to line a small enclosure with some metal fibers, can it?
Last time I went to DefCon, the SLNT Bags were petty popular. I didn’t buy one myself so I can’t speak to their effectiveness, but if the DefCon crowd trusts them I think they’re probably at least looking into.
I am not sure if I would trust a company that claims a glorified fanny pack will protect your health from EMF radiation.