It should be noted that even though bears can not open bear cans, they are perfectly capable of taking them to remote areas where they can toy with them at their leisure. Bears have even been known to get frustrated and throw bear cans into creeks, off cliffs, or into other unaccessable areas. Therefore, as fuzzy noted, it is very important to keep the odor of food off of these cans. Also, if you have two bear cans, and the time, you might consider counterbalancing them as if they were bear bags, to be extra safe.