Under Armour Fly-By Leggings Women's Compression Running Tights - Medium - Black Locked-In UA Compression Fit - Increases muscle power and reduces recovery time. Signature Moisture Transport System - Removes moisture from the skin to keep you cool, dry and comfortable. 4 Way Stretch Construction - Dries faster and improves range of motion. Flatlock Seams - Ergonomically flatlocked to give a superior fit and reduce chafing. Open-Hole Performance Mesh Insets - Regulate the wearer's temperature across critical heat zones.