A literal tinfoil hat, crudely made so there are no crisp, clean lines or folds-- it's as though someone crumpled up a wad of tinfoil and it happened to be able to sit on a humanoid's head. It is intended to protect your brainwaves from The Man (tm). No one is messing with YOUR mind! Nevermind the fact everyone around you stares and chuckles and no one takes you seriously, you KNOW you're not a conspiracy theorist! Unless... that's what they want you to think?

The wearer has resistance against Psychic attacks, however they also have disadvantage on any charisma checks.

Fits best on medium humanoids, is uncomfortable and even sillier-looking but wearable for those a size larger or smaller.
Unwearable for Tiny, Huge, and Gargantuan creatures.

Notes: Resistance: Psychic, Disadvantage: Charisma Ability Checks