We found that the HyperKewl vest works amazingly well under a mesh or perforated leather jacket. The length of time the soaking works depends on the temperature, humidity and the airflow through your jacket–expect anywhere from one hour to all-day.Fortunately, the vest can be soaked in any nearby sink or you can bring a plastic bag and fill it with water. In two minutes, it is ready to go again. You need a high-airflow jacket, but you’ll already want one on a hot summer day.The TechNiche HyperKewl Ultra Sport retails for around $42. For additional information, log onto the TechNiche website.