I find it difficult to believe that a bear can "rip" the hide off a tree but can not get into a bear "sack" !!!!! For some strange reason, I just find that very hard to believe. I would almost say the same thing for the bear canisters but I can see that it would be hard for a bear to get any type of grip on a bear canister. I think if given enough time with knowledge that there was food in the container, I would bet on the bear every time.