Details
What is Wii MotionPlus?
The Wii MotionPlus™ accessory takes the motion-sensing controls of the Wii console to new levels of precision, sensing gameplay movements with greater accuracy than ever before. Designed to attach easily to the Wii Remote controller, Wii MotionPlus brings every twist of the wrist or turn of the body to life, faithfully replicated on the TV screen. See the swing of a golf club or the slash of a sword revealed in vivid 1:1 movement—Wii MotionPlus elevates Wii gameplay to a level of realism that you never thought imaginable.
More Info
http://www.nintendo.com/wii/console/accessories/wiimotionplus