The Resideo 203369 Air Cleaner Pre-Filter, sized 12.5" x 20", is a durable replacement filter designed for Resideo and Honeywell air cleaner systems. It effectively traps larger airborne contaminants such as dust, lint, and pet hair before they reach the main filter, enhancing overall filtration efficiency. https://www.partshnc.com/203369-resideo-pre-filter-for-f50f-f300e