You should always buy
Lennox furnace filters replacements from original equipment manufacturer. This ensures that the original company that produced the product manufactured this replacement too. For instance, if you have a Lennox furnace, you would purchase a replacement filter that was manufactured by Lennox. With this you eliminate the chances of mismatch or a drop in quality or efficiency. Lennox furnace filters are always a better choice over any standard fiberglass filters in terms of efficiency.