Using your K&N HVAC filter is easy. First, measure your HVAC unit to make sure the 20 x 25 x 1 filter fits properly. Then, remove the old filter and slide the K&N filter into place. For maintenance, check the filter every few months. When it looks dirty, take it out and wash it gently with mild soap and water. Let it dry completely before reinstalling. Remember, don't use harsh chemicals or scrub too hard as it may damage the filter. With proper care, this filter will serve you well for the life of your HVAC unit.