FRONT SPROCKET: 824 K teeth number : 14 16CrNi4 Steel REAR SPROCKET: 1509 EC teeth number: 50 Aluminium Alloy 7075T6, lighthess and with mud grooves on both sides for off road CHAIN: 520MXZ4 plates number: 120 520MXZ4 is mode for serious motocross racer, lightest and strongest motocross chain available today! Feature chromoly steel construction with seamless rollers and bushings, and oversized special alloy pin with RK Special HCR Treatment for strong wear resistence.