There is a definate reason these everlasting treat balls are always sold out of the big local pet food stores- they are fantastic! My dog is a very rough chewer- he can even rip apart kongs, and he loves these treat balls. They don't last him for "hours" per say as the package states, but enough time that I am able to have him busy when we have company over. It's especially helpful if you insert a treat ball in both ends of the blue ball, making it especially challenging to pop out the edible discs. Not for an everyday treat obviously, due to quantity and prices, but I will definately buy them again!