Change your preferences here.
Boosts the holder's accuracy by 10%.
Not a great item, generally. A miss can often be the factor that loses you the game, especially if it happens at a critical moment. For this reason, you would expect Pokemon that carry lots of lower-accuracy moves, such as Heracross with Megahorn and Stone Edge, to happily take on this item; however, the 10% accuracy boost is not great, and you will miss the power from Life Orb greatly. If it were 30% accuracy, it would almost certainly see more use—as it is, it can only chance Focus Blast's accuracy from a miserable 70% to a slightly less miserable 77%, it isn't really worth it.
Castelia City - Talk to man in Pokemon Center after having acquired 5 different outsider ID numbers.