Men's Nike Flex Running Short - LIGHTWEIGHT TO START, COOL TO THE FINISH. Running your best requires gear that won't hold you back. The medium-length 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. Perforated outer short enhances airflow for cool comfort. Stretch Nike Pro inner short has side vents for increased airflow. Reflective details at the sides enhance visibility on low-light runs. Drop-in and zippered pockets offer convenient storage on the move.