The heat from body and surrounding air make the water inside the vest vaporise. It causes the surface and your skin to cool down in a dry way before you become sweaty. If finally, the reservoir is empty, simply reload by adding 500 ml of tap water and your are ready to stay cool for up to three days.
Linning: Water wicking polyester fleece
Function: Up to 3 days cooling with a maximum decrease of 15° Celcius with only 500ml water, Unlimited washable and anti-bacterial.