The Evaporative Cooling Vest (ECV) fits comfortably on the body with a zipper front. The vest comes in many sizes to ensure the right fit for you. Water causes a naturally cooling effect as it evaporates; these garments are made of a special fabric which holds the cooling energy for an extended period of time. Evaporative Cooling Safety Vest (ESV) is activated by simply submersing it in water for 1 to 3 minutes, or until it reaches the desired level of hydration. Gently wring out excess water and it's ready to wear! No freezers or cold packs necessary. Once activated, the vest will provide many hours of cooling relief. Evaporative cooling is especially effective in low humidity climates. Lightweight, unisex design with a zipper-pull front. Color: Blue, Marine Digital Brown or Army Digital Blue. Available in S, M, L, XL, XXL, XXXL. Fitted vest is not adjustable.