(hex:A2) is a glitch item in Pokémon Red and Blue.It is a Rival's effect glitch item, meaning that it will open a menu which if closed with B will allow the player to walk through walls that are one tile thick.
The glitch item acts as an evolutionary stone outside of battle with unknown compatibility. If the player attempts to use it from within battle, they will get Professor Oak's message that it isn't the time to use the item.