It is introduced in Baliren's blog:/s/blog _ 4ac1b 60100bhri.html.

But it doesn't seem to be aimed at cold stomach. If your stomach is always cold, you can stick a warm baby on the navel outside the autumn clothes. I feel very useful. My mother used to have diarrhea easily when she caught a cold, but it was basically normal to stick it for a while to warm the baby.