What Pika said.

Also, because I have run into people confused by this - you do not tie the bear can to anything, nor do you leave straps, ropes, or carry case (the Garcia model has an optional case you can use to strap the can to your pack) on the can when it is being used to store food. This only gives the bear something to grab and use to drag away the can, leaving you with no food whatsoever and giving the bear plenty of time to figure out how to drop the can on a rock to get in.

The can is round and fat so it can't easily be manipulated by a bear - if they could get their mouth around it, they could break the plastic. A couple of bears have figured out how to bite the tabs off the Bear Vault lid. Once bears figure out our food is really great stuff, they go to great lengths to get it, so really, whatever measure you take in regions where bears are habituated is just "bear resistant" - given time the bears will figure out how to get in.