I've purchased five different food dispensing toys. The 5-inch IQ Treat Ball, the Omega Paw Tricky Treat Ball, Large, the StarMark Interactive toy, and the Premier Pet Busy Buddy Twist N Treat Dog Toy, Medium, and the Premier Pet Busy Buddy Twist N Treat Dog Toy, Large. Please note that you cannot clean the insides of the StarMark or the Omega ball. Unless you want old gunk hanging around for months, these two toys will last ... very short. I kept each for only a couple of months before tossing them out. The only two I use to this day are the Premier Pet Buddy, Large, and the IQ Treat Ball. Of all of these, each one has its benefits and shortcomings: The Omega Paw Tricky Treat Ball is the perfect material for my dog - he's not a huge chewer. It hits the wall and makes a gentle "thud" sound. However, with the new design, the hole that dispenses the food is much too large and dispenses a ton of his treats right from the getgo - this is not enough to keep my dog entertained for more than a few minutes! The Omega Ball fits the most food - I believe I can get up to a full cup of kibbles into it. Note that the only way to clean this toy is to put water in it and shake. I made the mistake of putting dishwashing liquid in it, shaking, and trying to get rid of the suds. It didn't happen - the suds persisted. There's a tiny air hole on the other side... not that that helped get rid of the suds. I threw the toy away. The Premier Pet Busy Buddy Twist N Treat Dog Toy, Medium is my least favorite. Whilst it also does not make a lot of noise, you can't necessarily control how fast food comes out because it relies on twisting it just right- and when the toy is knocked around, it untwists, and just spills out all the food, too - well, at least makes the hole bigger so food comes out much too fast. This is my least favorite food dispensing toy. The Buddy is also the smallest - you can only fit 1/4 to 1/3 cups of food in here if you seal it tight. The one great thing about this toy is that you can actually clean it. The Premier Pet Busy Buddy Twist N Treat Dog Toy, Large, is my very favorite. It's sturdy, food comes out at a decent pace and when my dog knocks it around, it doesn't cause the opening to get bigger. I can put his entire meal inside this toy (unlike the medium size) easily and it's not a huge balancing act to make sure nothing falls out. I can clean it, and it doesn't roll away like the IQ ball into places my dog cannot reach. It's slow rolling so he can guide it easier. Plus, it's quiet and only makes a gentle thud. No matter the size of your dog, get the large. My dog is a 25-28 pounder. The large is much sturdier than the medium. The StarMark Interactive toy is very large. You can fit a lot of kibbles in there. That's a bonus. Also, you can make the dispensing method more difficult in two places. However, you cannot open the thing to clean it and I certainly would NOT put water in there, as it's odd shaped, and I really don't like what may happen if I try to pour water in there and shake. I would highly recommend that you start with this toy rather than one of the balls if you plan on buying a StarMark toy. The reason for this is that my dog was used to rolling or pushing a toy to get his food out. So instead of gently nudging the StarMark toy, he would try to roll it, which ended up being really loud for me. He has never figured out that you just need to push the top to get the food out and just pushed harder to get the thing to roll. Finally, the 5-inch IQ ball is perfect in the sense that it lets you control how fast it dispenses, but it's SO LOUD. My dog gets all worked up at the ball and gets very aggressive with it because of the loud noises it makes. He reacts to the noises and I think it gives him anxiety. Not to mention all the loud clanging makes ME have anxiety. I'm worried the neighbors will complain! Another thing about the IQ ball is that because it rolls so easily and fast and furious when my dog pushes it and it is so small, it often goes under a piece of furniture so that my dog can't reach it. So much for keeping my dog distracted so I can do other things - I often have to get up and get the ball for him out from underneath a piece of furniture. This was not a problem once for the Premier Pet Busy Buddy Twist N Treat Dog Toy and not so much for the Omega ball because it rolls more slowly and when my dog pushes it, it doesn't travel that far. Obviously this is not a problem for the StarMark toy, as that toy is quite large. Finally, the IQ ball only fits about a 1/2 cup of kibbles. There is a white enclosure to manage the dispensing of food. You can fit another 1/4 cup above the white enclosure, but it's a pain because you have to make sure none spills over to the side before twisting - hard to explain, but trust me, it's a pain. 3/4 cup of kibbles max, and only a 1/2 cup is easily put in.