Ive used the smaller packs, they have been in the jars for 4 months or so with no leakage detected. Might not be a bad idea to put the bags at bottom of jars in case one would leak, then it wouldnt damage much product anyway. I havent broken the seal on them yet, but everything looks great. Im also interested in long term storage, specifically for larger quantities of herbs. Ive read that vacuum bags in the freezer isnt recommended, but is there a better way to store for say 5+ years?