http://www.amazon.com/gp/product/B00A... How to Use Reusable Hand Warmer Gift & Reactivate to Reuse
Simple to use and reuse, just follow these simple steps. Still using the same ones 2 years later. Reusing is definitely better than filling the landfills. Environmentally friendly!
Solution is sodium acetate, non toxic, that crystalizes when you click the metal disc inside. It can then go back to liquid form by boiling. Best to boil a few at a time to save energy.
Great for when you need heat instantly for a short period of time, 20 to 30 minutes. If you want longer, take more out with you.