Twin Air filters are designed to increase airflow while ensuring the highest level of protection from dirt/dust. Design, high quality materials and superior construction deliver unbeatable performance and protection. For KTM 125 EXC, 125 SX (1986-1997), 250 EXC, 250 SX (1982-1989), 350 (1987-1991), 440 (1994-1995), 500 (1982-1997), 540 (1987-1995), 550 (1987-1995).