D.I.D SUPER STREET 530ZVMX-120 BLACK/BLACK - 690-64120BKD. I. Ds ZVM X Series has greater strength than the VX Series and is designed for heavyweight motorcycles with Tremendous Torque and Horsepower. The twisting action of the X Ring increases its sealing performance and its four contact points minimize power loss. The ZVM X Series' Direct Energy Transfer, born from our experience in MotoGP, means greater stretch resistance under load.