Jollyballs are the only ones I have experience with. Scary is correct, they were originally created as indestructible rubber balls to prevent boredom in stalled horses, they had handles and tasted like apples, and the horses would toss them around (hopefully) instead of cribbing or pawing incessantly. The same company now makes much smaller jollyballs (some with handles, some with rope toys) for dogs to use, and they're just as effective for entertaining kenneled dogs. Almost all of my dogs have them, their size and durable rubber make them a great buy (you won't be picking up chunks of rubber out of the kennels, or at least I haven't yet) and if you have a dog that can't be trusted not to eat rope toys, the handled balls still enable them to chew and throw it around. They're the best lasting boredom buster I've found.