Reason for purchasing: My two dogs - a 28 pound miniature australian shepherd and a 42 pound siberian husky would eat so quickly it was beginning to edge towards causing health issues. I needed to slow them down and stimulate their minds because they are both smart and energetic breeds.Size choice: The ball comes in two sizes and the cut-off is just under my smaller dog's size. I bought two of the larger balls because they hold two cups of food (something few of these types of toys will do) and because the size seemed more difficult for the dog to destroy.Dispensing: You can adjust it "once." There is a hole in each end of the egg with little rubber "fingers" sticking out from the egg across the hole. You trim these rubber "fingers" to adjust for your kibble size and how fast you want it to dispense. This does have some drawbacks if you ever switch kibble or wanting to make it easier then harder as the dog "gets the hang of it" as once the "fingers" are trimmed there is no changing it.Ease of use (me): Difficult to unscrew after use but that is fine with me. I would rather they stayed closed than open while the dog is batting, pawing and nosing the toy. As mentioned previously the larger version does hold about two cups (or a bit more) and so I am able to feed my dogs each their entire meals without refilling the balls. The balls are made of hard plastic and so on hard flooring will make racket - plan accordingly.Ease of use (dogs): I initially filled the balls, cut up a hot dog and put the hot dog under the ball. When the dog nosed the ball not only did she get the hot dog but kibble also came out. I repeated this with one hot dog per dog once. The next day I placed their kibble in their balls, and in their crates (to keep them from switching balls) without dinner bowls. After several minutes of sniffing around each dog began to paw, nose and flip the balls. The mini aussie will even make it spin on end across her entire crate to make it dispense more. I have owned the balls for roughly a month and the dogs know exactly what to do with them.In summary -Pros:Slows dogs eating down considerablyMentally exercises the dogCan be customized for different sized kibble and dog abilitiesAble to take rough play - my dogs purposely run them into the sides of the crates to make them dispense and there isn't one crackAble to hold each dog's entire meal - a huge reason I bought this one over others on the marketLarger size prevents ball from disappearing under furniture or appliances (I cannot speak to the smaller size ball in this aspect)Stays closedNeutral:Can be noisy on hard flooring due to being made of hard plastic - plan accordinglyCons:Can only customize "once" or only to make the ball easier and not more difficult