This variety ball set is great for my dogs. The blue and green nubby balls have squeakers. The yellow one is a full rubber context and the red one has a large tunnel hole in the middle for cheese or you can put small treats into the sides that have teeth to make it extra run. Obviously the red one is my dogs favorite.The lead picture on the Coopupet Dog Balls for Aggressive Chewers listing shows four equal sized balls. And the description made me think they're small, like for small dogs. So I ordered them.These are not small balls. I gave my small pooch the green squeaky one to start because it's one of the smallest two (the yellow is also smaller). She loved it at first but not for long. It's hard for her to get her [full sized-snout] mouth around.These are not four of the same sized balls. The blue one is significantly larger than the others and won't work at all for my dog to bite. The red ball is rather heavy; much heavier than I'd expect for a toy ball. See my picture with the measuring tape to get a clear idea. The listing really should remove the incorrect lead image, and also include diameter measurements for each of the balls.The green ball has the loudest squeak of any dog toy I've ever heard. Be prepared !!With the information I've shared here, if these balls meet your needs, go for it. But if you have a smaller dog you may want to pass on this set. They fall short of ideal.The squeakers in these suckers are LOUD! I thought it wouldn't be an issue because my dog usually bites them out before long, but these are lasting forever! Anyway, the balls are on the cheap side and are all varying sizes. But overall, they have lasted a while and he goes nuts for them. So probably worth the money, but won't buy them again.The review says it all - most of the images make these look the same size, but the green ball is very small, a little smaller than an average tennis ball besides the spikes. The blue ball is large, and the red and yellow ones are a tiny bit larger than an average tennis ball.That said - so far my AGGRESSIVE SQUEAKER of a lab has not managed to bust the blue spiky ball's squeaker, which is impressive for the price tag.The yellow and red balls in this set are much thicker and dense than the other 2. While they're more durable my doodle doesn't like them because they are heavy and have no give when he bites on them.The green and blue bumpy balls on the other hand are well loved. These balls are much thinner and at first I thought they were kid balls that you'd find in a cheap bin at a store's checkout area. I've been pleasantly surprised that they've held up well and are more durable than I thought. They bounce really well and the bumps have stayed on them even after being chewed on.I have two Danes and ordered these - per the photos, the balls all look to be the same size, but that is not the case. 2 balls are comparable in size and meant for medium+ dogs, but the other 2 are smaller and meant for smaller dogs, so they are useless to me - they are a choking hazard.