Arrows should point to direction of air flow. If blower is blowing down (downflow), then arrows should point down. If blower is blowing up (upflow), then arrows should point up. If not certain, check your furnace or air handler and try to determine if the flow to your registers in your home comes from duct connected to the bottom or top of your unit. This would be the direction the arrows should point. Hope this helps--my first input on this site.