1.) Made for the professional Supermotard & Motocross racer. 2.) MXZ chains - chrome alloy steel construction with seamless rollers and bushes, and oversized specially hardened bolts for added stability. 3.) All versions are heat treated by the RK exclusive HIT (Heat Induction Transfer) method. 4.) With a maximum stretchable stability of approx. 4,000 kg. 520MXZ is the strongest Supermotard & Motocross chain from RK available nowadays! 5.) Ideal for professional Supermotard & Motocross-Racing from 125 - 500 ccm.