The Chill-Its 6667 Wet Evaporative Cooling Vest is made with a lightweight PVA material that provides immediate cooling relief to the core area. The lightweight construction is designed with breathable mesh panel siding making it more comfortable than other wet evaporative vests that can be heavy to wear. A front zipper offers an easy on/off, customized fit. For best results, we recommend this body cooling vest be worn over a t-shirt and not covered by other clothing HOW TO ACTIVATE<