simple use, safe, re-use, functional, no need of energy, can be continued used more than 2days

it has absorbent bead inside the fabric.

very simple use, just immerse it into the water 20-30 minutes in the summer, them it will absorb the cold water and expand to be full. It keeps cool more than 2days when you use it in the summer.

Atfer your using, dry it and keep it in the dry place, you can use it the next year.