There is no such thing as an indestructible dog toy, but the Ziscs are extremely hardy and durable.  Prior to discovering them, my cattle dogs (and their friends and enemies at the dog park) tore their way through a half dozen "frisbees" of different manufacture.  Ziscs seem to last us, on average, about three or four months (while other "frisbees" lasted only days or weeks).  And we put them through hell with gnawing and tug-of-war, so "normal" use should extend the lifetime to years.  Highly recommended for "frisbee"-loving dogs.