Lawn mower filter Compatible with 3.5-4.5 HP, Q 45, Classic, Sprint, and Quattro engines,Use with 450-600 Series engines with plastic air cleaner housings. Brigg & Stratto Foam Air Filter Element, part# 698369. Protect your engine from dirt, dust and keep it running at peak performance by replacing the Air Filter. Improves airflow and prolongs engine life by providing clean filtered air while running. We recommend replacing your filters every season for best performance .Regularly replaced lawn mower filters improve engine . This is an replacement part. Please compare its appearance, shape and size with your original unit and make sure that it can fit your machine before ordering.