We wanted to train our Wheaten to retrieve and thought it would be fun to try with a frisbee in addition to her ball. During my research I learned that the hard plastic on most discs can be harmful with tough chewers and might break so we looked for a safer alternative and stumbled on the Zisc. While she has managed to puncture it with her terrier fangs, it has held up quite well and is still operational after nearly a year. She loves it!