We have a lab/great dane mix who is obsessed with chewing and chasing balls.  Big stong jaws and teeth on that girl [Abby]  This is about the 10th different ball I have provided her and this is the best.  Its been a couple of months and she is still in love with this ball.  I think she broke through the ball with her teeth [which she always does] but she is keeping it intact.  We put all her balls that survive in one pile and she will go and pick this one out for special attention.  Bigger than a tennis ball, but not too big.  very durable.  easy to throw.  she can't get it as slimy as a regular tennis ball.  Its a good deal