A cool vest made with highly absorbent material, providing a cooling sensation for 5-6 hours. - Color: Gray - Size: Asian XXL (XXL) - Cooling Duration: 5-6 hours - Material: Highly absorbent material - Design: Comfortable mesh design This type is used by putting 500ml to 1L of water in the back. I almost got heatstroke at work the other day, so I panicked and bought this. I was also considering a fan-type vest, but a colleague told me that the breeze from those is weak, so I went with this new water-cooling type. ^_^ My back feels cold and good. I can't live without it now, and I wear it everywhere. I wasn't sure about the size, so I ordered two, but I've gained weight recently and weigh 96kg, so I needed a 3XL. I'm selling the 2XL. ^_^ It's hot this year, so I recommend it. Maybe it's just mine, but the instructions were a little different. You just put water in the back, and then reuse it by putting it in the refrigerator. It's easy! ^_^ I recommend it! ^_^