D.I.D 520 ZVM-X Series Super X-Ring Chain - 130 Links - Black 520ZVMXB130ZSUPERBIKE STRENGTH D. I. Ds ZVM X Series has greater strength than the VX Series and is designed for heavyweight motorcycles with Tremendous Torque and Horsepower. LONGEST WEAR LIFE The twisting action of the X Ring increases its sealing performance and its four contact points minimize power loss. QUICKER RESPONSE The ZVM X Series Direct Energy Transfer, born from our experience in MotoGP, means greater stretch resistance under load.