These are so simple to use - just heat in the microwave for 1-3 minutes on high, depending on the strength of your microwave. These bags give off soothing moist heat. It will retain heat for up to one hour. These bags are wonderful for necks, backs, sore muscles or to take to bed on a cold night...perfect for arthritis, sports injuries, migraines, cramps or breastfeeding mothers. Since there is no electricity involved, these are safe for children to use on those bumps and bruises. Also safe for use in your pet's bed. Also, this bag can be put into the freezer and used as a cold pack. Simply place into a zippered plastic bag (so it stays clean and does not pick up freezer odors) and freeze for 1-2 hours or overnight. Take along to a game in the summer to keep cool! These are also great f