RK’s MXZ4 chains are made for supercross and motocross racing. MXZ4 chains feature chromoly steel construction with seamless rollers and bushing. RK’s Chromized pins drastically improve the wear resistance more than two times compared to normal non-sealed chains while absorbing shock loads from extreme jumps. All components are heat treated using RK’s exclusive HIT (Heat Induction Transfer) process. 420MXZ4 has a maximum tensile strength rated at 5,400 lbs and is suitable for professional level racing. This is the same chain that we run on our Factory race bikes.