Title: I love the concept, but fails to deliver.
Review: I bought a pack of these at a trade show about 4 years ago. I absolutely loved them. I have fibromyalgia and chronic pain problems due to a back injury. I used them almost every day during the winter months. Then they stopped working about six months into use. I would snap the button inside, but they failed to change all the product in the pack. I would boil them, but they wouldn't turn clear again. I finally gave up on using them. Really sad about it because I wanted to buy more in the bigger sizes. They would have been perfect for backcountry camping and hiking trips. Too expensive to fail so miserably.
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