The Race Ss Top Is Designed To Help You Keep Cool And Comfortable, So You Can Focus On The Road Ahead. It'S Made With A Lightweight Fabric That'S Quick-Drying And Breathable. To Promote Even More Ventilation, The Upper Chest And Back Panels Are Made With A Stretch Mesh Fabric That Allows Fresh Air To Enter The Interior. Additionally, This Top'S Flat Seam Construction Helps Reduce Chafing, Helping You Experience Fewer Distractions When Running.