Cryopak Hard Shell Reusable Ice Pack, 3x5" (Pack of 16)

These only stay cold for about 4 hours. I bought some of the Cryopak Flexible Ice Blankets and I felt those were far superior overall stayed cold for 12 hours or more and were easier to store in freezer. These do the job for lunch boxes, but if you are looking for an bag of ICE replacement for chests, get the Blankets; they work much better and allow you to line the inside of the chest and layer them between food, which helps radiate the cold. The Blankets might be more expensive, but the price is worth the difference in performance.

My family has been using these every day for three different lunches (1 to work, 2 to school) and not one of them has developed a leak yet after more than two months of using them. I was a little worried, because they seem to freeze with a pronounced bulge in the middle, and I thought it might crack the cold plastic. We keep about eight of them in the freezer every night, and stick 3-6 in lunch bags nearly every day. I still have the other 8 in the basement as backups when some do eventually break or get lost. These have proven to be a great bargain.

They appear to work fine and the size works for tucking them around the food containers in an ice chest or insulated bag. The seller does recommend using them in an ice chest, since it is better insulated than the insulated bags. The size also works for storing them in the freezer or using in a lunch box.

I thought because the majority of the reviews for this product were positive that the one negative was a fluke, it was not. The packs are a good size and keep things very cold all day in a lunch bag. That's the good. The bad is that they will bulge when frozen which isn't that big of a deal. After about 5 freeze thaw cycles the packs will crack in the freezer letting a clear goo leak all over the place (and I was very careful with them). That is a big deal. I don't think they would last a day in a kids lunch box. I've had other packs like this last for years of regular use. These seem to have some sort of design or manufacture flaw. I suppose they are fine if you only want to use them a couple of times and then throw away (hopefully before they make a big mess in your freezer).

Good size, convenient for small items; too soon to know for sure about these, but based on past experience with larger cryopak products, I'd expect a failure (crack/leakage) rate of about a third. There's plenty of them, though, and price was good.

those are strudy and live in a freezer with seasonal usage in a cooler. works for 3+ years so far

They do expand. Froze them once and the looked extremely bulbous, like they would pop. The plastic is not malleable so my guess is reasonable. I even laid them down flat as I thought that might avoid the problem of the puffing up that other commenters mentioned--didn't work. Haven't popped yet, and I've frozen them twice.

I wanted the larger size but these work fine.