Keep your air purification system running its best by replacing the filter every 6 months. When its time to replace the air filter in your Lennox PureAir air purification system, trust the Lennox Filter Replacement to keep your air clean, clear, and breathable. This air purifier replacement filter is Lennox part number X8788 with the model number 100908-07. Use this replacement air filter with Lennox PureAir air purifiers with model number PCO20-28. This replacement air filter measures 20 inches long, 26 inches wide, and 5 inches high. Designed to keep your air clean, this air filter is rated at MERV 16 efficiency. This means it can filter out particles in the air as small as 0.3 microns. Breathe easier in your home by replacing an old or dirty air filter with this Lennox Air Purifier Filter Replacement.