We have used these cold packs multiple times now, and they have worked well for us through several freeze-thaw cycles. We are always careful where we place the freezer packs in the freezer and in containers to avoid poking holes in them. One hole and they are pretty much done. We have learned by experimentation that there is an optimal way to keep any food cold, or frozen, as the case may be. First, be sure the food container is insulated, and insulated well. Second, pre-cool the insulated container as much as possible. For frozen food, we pre-cool with dry ice if we can get some. Ice also works, but dry ice takes the pre-cooling to a much colder level. Third, remove all pre-cooling materials and remove any residual moisture. Fourth, fill the insulated container as much as possible. Fifth, add cold packs in any location where gaps or spaces remain. Since the cold packs are added last, the cold packs should be near the top of the insulated container so that the cooled air sinks from the top to the bottom. The advantage of the freezer packs is that they do not drip onto food as they thaw, assuming the packs have no holes! We have successfully shipped frozen food across the country (next day air) using insulated shipping containers with freezer packs and the food has arrived safely. We do not ship with dry ice because while dry ice is permitted on planes, dry ice requires "special handling," which means big dollars, so we stick to using dry ice for pre-cooling only, and pack as close as possible to the time of shipping. Admittedly, there are other options to using freezer packs. However, these are reusable and their rectangular ship is quite suitable for our shipping containers. Occasionally one develops a leak. We have not had any success in sealing a leaking freezer pack, so we dispose of those that leak. The other problem is getting the freezer packs back. Those we send locally we can usually retrieve. Those that go cross country become gifts to the recipient, which needs factored into the shipping cost. There are a few complaints about shipping costs, but generally most recipients are happy to have their food intact and edible and understand that the packaging does exactly that. Freezer packs meet a very specific need, and these are reusable, with care, and are reasonably priced. When used as part of a shipping process for cold or frozen food, they work great. Enjoy!
