RK 520MXZ5 applies the HCR Pin and special alloy steel for component making, resulting in a tensile strength as high as 35.6[kN] with weight as light as 13.7[g/L].

RK 520MXZ4 features special alloy pins with RK special
HCR Treatment (High Tech Chromium Carbide Layered Pins) which
drastically improves the wear resistance of the Pin while absorbing shock loads from extreme jumps.