I bought our cocker spaniel the medium size which is just right, and he loves it! We put the easy treat paste in it and send him outside with it and he spends ages enjoying it. We like that it is also helping his teeth. The grooves are pretty narrow which keeps him occupied as the paste is hard to get to, but it does require a bit of extra cleaning as some of the paste gets stuck in the grooves.

My dogs love this one more than the normal Kong... it seems to really help their teeth and keeps them entertained for ages..

This toy is not kongs best invention. My staffie destroyed it within 5 minutes of having it. The toy would suit a dog that dosent have a very strong bite force.