These body comfort heat packs really work. I have them as well. They have a silver metal disc you press inside of them and they automatically start to heat up and become like a solid substance. They get hot and stay that way for about 20 minutes or so. They get harder as they cool and you boil them to reactivate the gel again. Then you just press the silver disc inside and the process begins again. This bundle comes with 2 pocket hand warmers, 2 hand packs and 2 foot packs as well. They are wonderful for pain and arthritis as well as blood circulation. If you have pain often, this will really help. I use them as well as the ones for the back due to a car accident. These are still in cellophane and were never used as they were from an estate.