Usage: 
Make the liquid bag broken in the ice bag; then shake the bag up and down to make the content fully mixed, and the temperature will be under zero in 2 minutes.
Purpose:
Remove the pain and discomfort induced by fever, headache, toothache, mosquito bite;
Keep food fresh.

Precaution:
Only be used externally.

To avoid a too low or a too high temperature, enwrap the cold/hot bag with a towel.

Characteristic:
Easy to use.