Material diffused into body
First of all, there is no size to choose and they gave me a large size for my 32&#34; waist. It did self heat up fast and later on, a little bit too hot. Then I took a bath. The next day I did not use it and went out with a coat. But I could feel my belly was warm in the street. The same  holds true when I meditated. Obviously some material diffused into my belly already. I don't know if that material is harmful.
Rating: 1 stars