Twin Air Filter to fit Kawasaki KFX 400 Quad. Twin Air is the world leader in Dual Stage foam air filters. The filters provide the best combination of air flow and protection for your ATV engine. Just ask riders like Chris Borich, Dustin Wimmer, Adam McGill, and Cliff Beasley. These riders trust our filters to get them to the finish line. Every Twin Air filter is constructed from two layers of open-pore foam that are bonded together to provide maximum filtration and superior airflow. A coarse-foam outer shell is flame laminated with a fine-foam inner core, resulting in a one-piece design that is both functional and durable. Please note that we use a sample image, you will only receive 1 filter and your filter will require oiling.