When they are used properly, yes, bear vaults or bear canisters do work. They will need to be closed and locked so that the seal is correctly in place, which will prevent any bears from getting to your food or scented items.  It is worth bearing in mind that bear canisters aren’t 100% smell proof, so it will still be important to store them at least 200 to 100 feet away from your campsite to keep you and your fellow campers safe from bears. You may wish to purchase odor barrier bags as well to prevent bears from scenting out your food.  It will also be important not to attach anything like ropes to your bear canister as these will make it easier for a bear to carry your canister away from the camp.