Item from Percy Jackson by Rick Riordan
A New York Yankees cap that turns the wearer invisible — a gift from Athena, used by Annabeth for stealth, scouting, and the occasional dramatic entrance.
The Yankees cap is Athena's gift to Annabeth — practical, effective, and deeply New York in a way that suits the goddess of strategy. A completely normal blue New York Yankees baseball cap that turns the wearer invisible the moment it's placed on the head. It provides perfect invisibility but not silence, so Annabeth has to move quietly and control her breathing when using it for infiltration. She uses it for scouting, ambushes, and sneaking past monsters who never see the knife coming. It temporarily stopped working during the Mark of Athena arc when Athena was angry at her daughter — the divine equivalent of taking away a teenager's phone as punishment.
A completely normal blue New York Yankees baseball cap. Put it on and you vanish. Annabeth wears it so often that her friends have learned to talk to empty air.
Also known as: the Yankees cap, Annabeth's cap, the cap of invisibility