Men's Nike Flex Running Short - SUPPORT PLUS VENTILATION. Running your best requires a fit that won't hold you back. The short inseam of Men's Nike Flex Running Short pairs the stretch and support you need from the start, plus optimal airflow to keep you comfortable as you head towards the finish. Nike Flex fabric stretches with your body allowing optimal range of motion. Dri-FIT technology moves sweat away from the skin to help you stay dry. Perforations increase airflow. Built-in short with mesh panels deliver breathable support. Drop-in and zippered pockets offer convenient storage on the move.