The KONG ball comes in two sizes; I have several of both sizes and they are the longest lasting "fetch balls" I have bought for my dogs. I used to buy tennis balls and have them all over the yard but they would get muddy or water logged which resulted in them not bouncing. Even though the KONG balls cost more than a tube of cheap tennis balls, they last long and as soon as the dogs see me pick one up to throw it they are super excited and ready for some fetch. The small KONG ball has a hole in it so you can add a treat to it; even if you add something to the inside of it you are still going to be able to bounce it. The larger dogs will go after this if I throw it but they aren't all that interested in trying to get whatever is inside it if I slide a small bone or piece of kibble in it. The large ball is solid and I can launch it all the way to the back of the yard with no problem; I think they have only destroyed one of these since I started buying them. Most of the pet stores in the area have KONG products but they might not have the ball in both sizes. This past Christmas my dogs got a couple of the large balls from friends as well as the Extreme KONG (black version) ball. For whatever reason they don't play with the black one (Extreme) as much as they do with the regular red KONG ball; maybe it's the color or the way that it bounces but they clearly like the original version more. If you have a dog that is tough on balls or you want something that is easy to clean then this is something that's worth the selling price.