Yo-yo water balls (and similar products) are toys that are intended be thrown and returned to the hand. They usually have a loop on one end of an elastic cord to wear around the finger and a soft synthetic object on the other end.
The object which is attached to the elastic cord may be filled with liquid, air or a novelty item such as a flashing light and/or it may resemble a cartoon animal.
Yo-yo water balls are unsafe as the cord can cause strangulation. The liquid filled centre may also cause illness and skin reactions.
Because of these risks, yo-yo balls (and similar products) have been permanently banned from supply.
However, the ban only applies to these sorts of toys which have an elastic cord capable of extending at least 500mm in length. Be aware that although the cord may initially appear much shorter than this, it may reach or even exceed this length when its stretched. Also, the ban does not apply to outdoor and sporting toys. For example, a ball which is used to practice tennis whose elastic tension cord is intended to be anchored.