According to CPSC, "The wrist straps are sold with Nintendo's Wii video game system (pronounced "we"). Its controller, called the Wii Remote, is shaped like a TV remote. Sensors determine the Wii Remote's position in 3-D space, which means that a tennis swing, for example, is done through movement of a consumer's hand rather than by just fingers and thumbs. The cords on the wrist straps included in this program are 0.6mm in diameter. The replacement cords are 1.0 mm in diameter"
The problem with the wrist straps is that if someone swings the controller around, and then lets go, the wrist strap can break, thus launching the remote into the air! Nintendo has recieved numerous reports of the strap snapping especially while playing the Wii Sports game. Consumers who have purchased the Wii can contact Nntendo for a replacement wrist strap.