Kreitler Killer Add-On Headwind Fan 100-Percent Made in the USA The main function is to add resistance; An adjustable air inlet controls the amount of resistance desired; When closed, the additional resistance is minimal; Wide open, the resistance is high enough for even the strongest riders The second function is to provide a cooling breeze; The Fan unit can be rotated to point the airflow high or low, and adjustable louvers can fine tune the side-to-side direction Staying cool will make your workouts more enjoyable and is less stress on your body The Fan attaches to the front left side of the Frame; You can also direct the airflow away from you if desired