The bag is heated up to more than 50 degrees centigrade when friction is made for one or two minuets. It generates heat for 1,500 minutes.

What is noticeable is that the bag radiates far infrared rays and anion.

Ro Hye Ok, a Pyongyang citizen, told KCNA that she felt relieved from pain after using the bag.

Kim Song Hyon, manager of the Kumchon Exports Production Company, said his company would soon begin making portable cooling bags, too.