Purchased after November 2011 which is the date stamped on the bottom of the cans . I called the one 800 number and spoke to a representative who said i could send a picture of the defective cans which i did then was told he needed to talk to a supervisor about my swollen cans x3. Well never heard back so i contacted the agent again, this time i was told that they would not exchange my cans because they didn't carry these specific types any more and it was left at that. well i thought that they should have lasted at least ten years plus but at this rate seems not .