Under Armour HeatGear Flyweight Run Split Running Shorts HeatGear Flyweight Fabric - Lightweight and smooth, this functional material blend sits comfortably against the skin whilst delivering peerless technical performance. Perforated Rear Panel - Allows air to permeate the short and ventilate critical heat zones. Moisture Transport System - Wicks excess sweat away from the skin and onto the garment's surface, from which it evaporates. Anti-Odour Technology - Quells the spread of odour carrying microbes. Reflective Components - Preserve the wearer's visibility in diminished light.