This is the Brain Coat from Filter EMF. It's a $55 nylon skull cap with ear flaps that's been coated with silver to help prevent radio frequency waves from penetrating your brain like the government wants. Plus it kinda looks like the kind of condom I'd imagine a knight wearing. Some more infos:
Microwave Shielding Effect: >35 dB at 1-10 GHz
Surface resistivity: <0.5 Ohm/sq
The Brain Coat- RF shielding for your mind is a silver coated nylon skull cap with ear flaps. It is a lightweight cap that breathes nicely. It is very comfortable to wear it round your ear while sleeping. It is also very thin making you able to wear it under conventional hats. You can also tuck ear plugs under it and can get an unaffected sound quality. The Brain Coat provides your brain a quiet place without any interference in your mental processes.
I have no idea what any of that means but I just bought one because my brain is important to me. After all -- our brains are our most valuable commodities. Unless you're one of my idiot friends, in which case your brain is probably garbage and your most valuable commodity is my friendship.
Thanks to Dave L, who informed me he plans on wearing two at once for DOUBLE PROTECTION. I'm not sure that's how it works, Dave. Just kidding, it totally is -- smart thinking. I can see why you'd want to protect that noggin.