Aprilaire filters, also known as Spaceguard filters, are some of the most popular in the market. Would you believe us if we told you our aftermarket versions perform just as well but are priced at a fraction of the cost? If you don't believe us, try them out for yourself. We offer free shipping and free returns within 30 days, so you can give them a shot without the risk. If you choose the right size for your Aprilaire filter replacement, you shouldn't have any issues inserting the filter into your HVAC unit. Before buying, you want to make sure you have the correct measurements. Once you do, double check that the arrows on the filter are pointed in the right direction. They should indicate which side faces the outside air. If you have any trouble with your Aprilaire air filters, do not hesitate to contact us!