(hex:7C) is a glitch item in version 1.0 of Pokémon Yellow (Japanese).When it is used from both outside of and within a wild Pokémon battle, the game may throw a Poké Ball with many rolls which eventually may lead the game to freeze.
However, if this glitch item is used in a Trainer battle it has the highly useful effect of immediately catching whatever Pokémon the Trainer has currently sent out. A copy of this glitch item will also be used up.