Under Armour HeatGear Flyweight Run Singlet Running Vest Imported Ultra-Light, Smooth Fabric - Provides extreme comfort and performance. Mesh Panels - For great ventilation and breathability keeping you drier and more comfortable. Signature Moisture Transport System - Wicks sweat away from the body, keeping you cooler and drier. Anti-Odour Technology - Prevents the growth of odour causing microbes. Smooth Flat Lock Seams - Allow a full range of motion without chaffing.