Under Armour HeatGear Flyweight Running Shorts - Medium - Grey Imported Ultra-Lightweight Woven Fabric - The fabric is durable, lightweight and breathable. Perforated Side Panels and Back Waist - Provides strategic ventilation, offering breathability and helping to keep you cool during exercise. Internal Mesh Liner - Helps moisture to escape, and provides breathability to keep you cool and dry. Anti-Odor Technology - Prevents the growth of odour-causing microbes to keep you fresh during exercise. Reflective Detailing - Ensures 360 reflectivity during low light conditions to keep you safe.