Using your K&N HVAC air filter is easy. First, turn off your HVAC system before removing the old filter. Insert the 18 x 30 x 1 K&N filter in the correct direction as indicated by the arrows on the filter frame. Then, turn your HVAC system back on. When it comes to maintenance, check the filter every 3 months. If it looks dirty, remove it from the HVAC unit. Wash it gently with mild soap and lukewarm water. Let it air dry completely before reinstalling. Avoid using harsh chemicals or scrubbing too hard as this can damage the filter. Remember, this filter is reusable, so there's no need to replace it with a disposable one. Keep enjoying clean air and savings for the life of your HVAC unit.