1999-2004 Honda 400EX TRX400EX Red O-Ring Chain and Silver Sprocket 13/39 94L 13 Tooth Front Sprocket, 39 Tooth Rear Sprocket and 520-94L Red O-Ring Chain All Race-Driven sprockets meet or exceed OEM specifications and use hardened S45C steel. O-Ring Chain helps keep the pins lubricated which reduces friction and helps the chain last longer. Fits 1999 2000 2001 2002 2003 2004 Honda TRX400EX TRX 400EX