I have some of them which have been stored in kits since January 2009. They were not treated with kid gloves, but they were not pounded or stomped on either. I was going out to teach my Scout troop wilderness survival in March this year, one task of which is to start a fire three different ways. As a test, I used all of my Sure-2-Burn packets, just to see how they held up for 3 years. All of them lit with no problem. Several I opened up and tested with various spark type fire starters, and they all lit. I don't think I would trust them if they had been exposed to air. None of the packets had opened up though. They store nice and flat, they are flexible, and they are light. All of that said, however, I always carry multiple types of tinder in my kits: Tinder-quick, cotton balls and petroleum jelly and then something else like the sure-2-burn or Esbit cubes. I don't like to be in a position of being dependent on one method to save my life. Just like carrying multiple tools to start the fire: lighter, storm proof matches and a spark type fire starter.