The Choice Scarf (Japanese: こだわりスカーフFixation Scarf) is a type of held item introduced in Generation IV. It has two counterparts that boost different stats: Choice Band and Choice Specs.
When held by a Pokémon, it boosts the Pokémon's Speed by 50%, but only allows the use of the first move selected. This effect resets when the holder is withdrawn or when the item is removed in the absence of Magic Room.
In Generation VII, if a Pokémon holding a Choice Scarf uses a move other than the one it's locked into (such as through Embargo or Dancer), the move will fail and no PP will be consumed.