I have had one for about 10 years. In the USA they call it a re-heater. Mine is the 8" X 12" version. I like it very much. The gel has become much more crystalized with age, but it does not seem to affect the heat output. I like mine better than the chemical packs (it is much larger) but it is heavier as well. I'm glad to see they still make them. I may buy another one.