I had such high hopes for these but they did not live up to their promises and I will not be purchasing them (I tried them through a free sample). I found that they felt weird and uncomfortable on my skin and didn't really heat up to a temperature that did anything to relieve pain/discomfort.
They are also quite expensive for something that you might be using quite a lot.
I liked these patches, it was really nice to have a direct source of heat where I wanted it. It also gave me a bit more freedom to walk around and carry on as usual instead of having to sit there with a wheat bag or hot water bottle. I liked this product but I would probably not purchase them often as they are expensive.