The "Dynamic Duo," (a male Westie and a female Scotty), have three criteria when they evaluate a toy: 1) Do they like it; 2) Is it safe; and 3) Does it stand up to repeated abuse and gnawing, (the "durability" factor)? Based on these criteria, the DD say, "Four Stars," for the large Dr Noys Chipmunk. After 6 months of being chomped, tugged and mauled - the Chipmunk pretty much looks like it did in the beginning - including it's tail. One caveat: The DD are "small," (20 pounds each), dogs - but the "large" munk suits them fine - except for the very smallest dogs, (or perhaps puppies), I recommend sticking to the large version.