I believe most store bought Zip Locs are less than two mil. If I were to encapsulate these kits ( I too have avacuum sealer) I'd include the heavy zip locks within the vacuum bag. Not only can these heavy bags be used tor other purposes but once the vacuum seal bag is broken open (in the field) it no longer can be closed. The 4 and 6 mil bags are typical in weight to what the military uses.