Air purifier pre-filter features an advanced design to capture harmful gasses such as ammonia and other volatile organic compounds to help you create a cleaner environment. Activated carbon and zeolite help reduce common household odors to keep rooms smelling fresh. Pre-filter will capture larger particles such as dirt, lint, fibers and pet fur. Easy-to-install design allows quick, simple replacement to ensure optimal performance. For the best performance, this air purifier filter should be replaced every three months.