Fieldsheer by Mobile Cooling 's Hydrologic vest uses a Super Absorbent Polymer (SAP) fabric with a more absorbent interlining that absorbs and holds cool water for extended cooling in even the hottest conditions. Designed for anyone that is in the heat for prolonged periods and needs rugged craftsmanship with high-vis features, this vest offers lasting comfort in even the hottest conditions. Soak the vest in water for 1-2 minutes, wring out excess water, and wear it over your work shirt to cool your core through evaporative cooling. The evaporation process pulls heat away from your body providing an instantaneous cooling effect. It helps maintain a safe, comfortable internal temperature throughout the day in the hottest conditions, made from low-profile, lightweight materials that store quickly when not in use. Its powerful cooling capabilities allow you to stay cool through the day no matter how hot it gets. Designed for workers in industrial professions who need high visibility and outstanding performance to keep them cool, comfortable and safe no matter what the day throws at them. Whether it's hot indoor environments or a construction site in the heat of summer Fieldsheer 's Mobile Cooling technology keeps you cool so you can get the job done. Utilizing quilted Hydrologic absorption and evaporative cooling, this vest provides cool comfort all day long.