The Chill-Its 6665 Evaporative Cooling Vest is made with an advanced polymer-embedded fabric to provide workers with immediate core cooling relief from the heat. This lightweight cooling vest is made of comfortable and durable quilted nylon exterior with mesh side panels for ventilation and stretch. Wear this body cooling vest over a t-shirt. A water-repellant liner keeps the interior of the vest as dry as possible when activated, though wearers should expect to feel some dampness\/wetness. Evaporative cooling technologies such as embedded polymers are a simple, effective and comfortable solution for heat stress prevention. Similar to how sweat cools the body, evaporative technologies use an external water source to draw heat away helping to regulate body temperature while providing cool relief. In order to activate, soak in water for two to five minutes. The embedded polymers will retain water for up to four hours of cooling relief. Hand wash as needed and hang to dry.