These have worked very well for me when placed into 7mm thick mylar bags to preserve foods that I have freeze dried. Push out as much air from the bag before you seal it for best results. You will notice after a few hours that the oxygen absorber will pull in more air causing the bag to collapse. Although this does not happen all the time so don't use this as a measure of success. Just make sure your food is dry to the touch and seal everything properly. I extremely recommend that you vacuum seal the absorbers that you don't use along with the freshness indicator. The color of the indicator will change after several hours or so to indicate that all air has been removed. Don't panic if the color tells you that the absorbers are bad when you first seal them. Just wait for a few hours and check again. It should be bright pink.

I got these to replace another brand that I used, did nothing and packs never even got ahrd. These from FreshUS work well, I put 5 each into a mylar 1 gallon bag - yes, way overkill, but I only had two bags to fill, and these come 10 wrapped and sealed, so once you open them, I try to use tehm. You can put them in a mason jar, but they have been exposed to air, so you will get less bang the next time you use them.

I did not want to write a review until I had an opinion out of true experience and not just impressions. These little packets are great and do keep the food fresh for months. I did two batches of sealed jerky, one with the pack and one with out. The one with the packet was fresher and packed a lot more flavor. Worthy investment if you ask my opinion.