I'm using the biggest Kong there is. Not sure which size it is, but on the chart, its as biggest as it goes. I don't think putting a smaller size kong inside will make a difference for my dog. He gets as much as possible from the big hole in the Kong. When he cant get the stuff out, he gets fustrated and slowly chews off the top, chunk by chunk. Then the filling will be exposed.
I never knew Kongs has some kind of warrenty. :roll: I gotta look into it when I go to the pet store. I went through like 6 kongs already.