None of the canisters sold are "bear proof". They are "animal resistant".
In nearly all cases a bear will give up and find something easier - the issue being in a bear that learns how to get around it. That behavior can and does get shared to the offspring.

Keeping a clean camp and scaring off bears is something that we shouldn't forget how to do - even with canisters. We must not let a bored bear sit there and have the time to figure out how the food jug works......