This disc is by far the best ever that we have tried. In a family that breeds border collies and papillons, we go through many discs each year. However, this one stands up to the challenge....even with our 57 pound border collie, "Blaze," who has also been nicknamed "jaws." He has been known to play fetch with an 8' long 2 x 4 and loves to be naughty by chewing on gutter downspouts and other heavy objects. Fortunately, he has mostly been trained out of this behavior - he tried to chew up the Zisc, but to no avail!
The only drawback to this disc is the weight....it is difficult to keep the disc aloft without throwing it farther than the dogs can run. Otherwise, this product is fantastic - keep up the good work!