These ice packs are AMAZING (will explain the Subscribe & Save caveat). I have chronic pain so I have 2 sets of the ice packs I need that are in a constant rotation. Why you need it: * Once fully frozen, it really does last up to 8 hours. I easily get 6 and usually the full 8. I'm sure the conditions and amount of insulation being used affect this. * You won't find any other kind that stays colder or for longer- I have tried them all, trust me. * The covers they come with are excellent insulators (which you will NEED). The straps are also super helpful for various situations since the strong velcro can stick to any part of the cover. Wrap around any size limb, or use to wrap around/ attach to stuff (I use them to hang the ice pack against the back of my wheelchair for back pain). * Even if only partially frozen, can get a lot of use out of them * The bumps are not uncomfortable * There are some easy work-arounds to some of the problems Tricky things to know/ keep in mind: * They take a long time to get fully frozen, and freeze best with air space in the freezer. I've found it takes 3-4 hours to get completely frozen. The blue bubbles will freeze hard first, then the pink liquid "matrix" will freeze last, and that's where the magic is, you need that pink stuff for it to last longest. * It's not that moldable when fully frozen, but if you use it when the pink isn't completely frozen yet, then it will bend more, along the gaps between blue bubbles. * There's a reason they're offered on "Subscribe & Save"! The pink stuff will eventually leak out (and get stuff wet), and with continued use some of the blue dots will also pop and leak out. Without the pink matrix, you can still use it with just the dots, but it's not nearly as long-lasting (freezes faster though). So with constant daily use like me, you'll need to replace them after about 4-6 months. (I don't recommend actually getting on S&S, just replace as needed.) Work-around: Always keep these in a 2-gallon ziplock bag! Doing this has extended the life greatly, and prevents the liquid getting on things when they do leak. (You might need to replace the bags once in a while but that's better than losing the liquid.) I also duct-taped around the edges of a couple of my ice packs, but it's unclear if this has made much difference, I can't tell where exactly the liquid gets out. The bags are most important. Pics- 1) a fully frozen one I've been using for about 6 months, in a ziploc bag. One or 2 blue dots have popped but nothing leaking, so it's fully functional 2) A thawed and "dying" ice pack- several blue bubbles have popped, the pink has begun to leak out (my bag is worn out too), I will have to replace this one soon to get 8-hours of function per use 3) This is a frozen but completely leaked out one, the pink is gone (I didn't have this in a bag!), I can still use it for some things with just the frozen bubbles, and it is flexible but will thaw a lot more quickly. (Side note- the 6x12 don't last as long as the 12x12.) The bottom line/ TL,DR: these are definitely worth it despite the leaking requiring you to replace them periodically. They're the best and only solution for nearly all-day use for chronic pain and/or taking on a day out.