I know the round 'pancake' tins are vacuum sealed. This is why they're so hard to open. It looks like most of our domestic blenders have gone to the pull top tin. I believe I can trust a vacuum sealed tin to keep the product fresh for 5-10 years. There is a bit of air in the pull top tins. I'm comcerned about the quality of the tobacco that has been in a pull top tin for that same amount of time. Can anyone tell me if one type of tin is better than the other? Thanks!! Ol Brokedik.