These little heat packs are amazing. They heat up fast, and are very convenient. I keep these in a small bag, in my purse with some tampons. They are great for lower back pain. They work good for cramps too. I have very bad back pain and stomach cramps during that time of month, sometimes they are so bad I just stay in bed with a heating pad. They are easy to use, just open the pack, allow to heat for about 5-10 minutes, and peel & stick on skin or on shirt. I like that I can use these while i'm out, instead of being stuck home with a plugged in heating pad. They are also very discreet, no one will know you are wearing it. The pads provide non-medicinal, 100% natural heat therapy without any side effects. They are light-weight, portable and the adhesive works well. They provide 12 hours of continuous heat. You can purchase these heat packs here! I received these in exchange for an honest review.