Abjure hats are magic items created by hat magic that can be used by anyone, including non-casters, to send small items, like messages and gems. Conjure hats can be used to receive them. Some hats are dual use, able to both send and receive. To send something, the user must wave the wand associated with the hat and say "Hoffa". To receive, the other person must wave their wand and say "Livingstone".
It is possible for these hats to give an armor bonus.
Real World References
"Hoffa" is a reference to a Teamster leader who famously disappeared. "Livingston" is a reference to an explorer who was famously found.