1) Made for professional Supermotard & Motocross Racer. 2.) MXZ chains - chromium-alloyed steel construction with seamless rollers and bushings, and oversized specially hardened bolts for additional stability. 3.) All versions are heat-treated by the RK exclusive HIT procedure (Heat Induction Transfer). 4.) With a maximum tensile stability of approximately 4,000 kg. 520MXZ is the strongest Supermotard & Motocross chain of RK is now available! 5.) Ideal for professional Supermotard & motocross racing 125-500 cc.