DID #520 MX Racing Chain - RJ - Clip The non-sealed 520MX boasts our highest rated tensile strength among non-sealed chains at 8,930 lbs. and properly handles the beating that chains take during tough, off-road races. Trusted and used by teams and champions such as Troy Lee Designs/Red Bull GasGas, Red Bull KTM, 8X ATVMX champion, Chad Wienen, and more! Because of its incredible strength, this is the go-to chain for riders across a multitude of racing disciplines, especially among the 450 class.