The heat last long and it works very well. I bought it for the trip to Colorado for skiing. It keep me warm inside. The only concern is I wish it is smaller size so it is lighter.If you suffer from Anemia and travel alot. I find that using these to attach to a travel blanket is great for maintaining core body heat. Hope this helpsWow! These last for a whole 24 hours. They’re great for period cramping, muscle aches or just to warm you up when it’s super cold out.My son is a ski racer and it can get really cold standing in one place watching him race. The Yaktrax Adhesive Body Warmers work so well. I stick them to the inside of my baselayer at the bottom, near my lower back. Make sure you order the one with adhesive because they also sell body warmers without adhesive. That said, the ones without adhesive are good for your pockets as back up hand warmers. They come in a 10 pack, which is convenient.love these heat patches. They stay functionally warm for at least 12 hours. The adhesive is pretty good but would prefer it stick a little better.I had purchased a 40 count pack of these and only received 5 in a box when I it came in.These took 30-60 minutes to fully warm, but stayed warm for well over 12 hours. I placed one on my back while tent camping in 20 degrees and I stayed toasty warm...used it as a hand warmer in the morning. I’m buying more for my cold New England winter hiking and biking sessions.I would give zero stars if I could. These were clearly from last year or the year before. The material inside the individual packet was clumped and wouldn't heat. I opened four of them for a cold motorcycle trip. I gave them 45 minutes to warm up. I shook them to get the air to activate them. One got lukewarm, barely warm really. The other three were not warm at all. These packages should be date coded. I would have sent them back and gotten fresh ones at a local store. Terrible. The only good thing, which didn't redeem a product that didn't work, was that the adhesive was good. The not warm packets stayed in place.