The First Aid Box is an item in Resident Evil 3: Nemesis.
It is designed to carry three First Aid Sprays and can be re-filled. The container increases the chances of surviving an encounter with "the pursuer", as it is the equivalent of two more opportunities to get out of the "DANGER" mode.
In EASY, the box comes at the start of the game in Jill's inventory, but must be earned from a Nemesis encounter in HARD. Carlos Oliveira will also spawn with an F. Aid Box if playing the game on EASY mode.