Kunai Knife

Kunai knives—leaf-shaped blades often used in martial arts—are allowed in carry-on baggage only if the blade is 6 cm (2.4 in) or shorter, and only when flying through Domestic or International (non –U.S.) checkpoints. Knives of any length are not permitted at U.S./Transborder checkpoints. When in doubt, pack it in your checked baggage to avoid delays.