1) Made for professional Supermotard & Motocross Racer. 2.) The lightweight high performance racing chain is the result innovative metal alloys and the latest manufacturing technology. 3.) MXZ chains - chromium-alloyed steel construction with seamless rollers and bushings, and oversized specially hardened bolts for additional stability. 4.) All versions are heat-treated by the RK exclusive HIT procedure (Heat Induction Transfer). 5.) 420 MXZ high performance racing chains are among the strongest in its class and have an excellent price-performance ratio based on all MX Racing Chain in the world!