Xray XB4 Composite Front Suspension Arm.

XB4 front lower suspension arm made from super-tough, high-tech composite material. The exclusive composite mixture used for suspension arms gives a perfect balance between reliability and performance; the suspension arm is rigid enough for a responsive feel and extreme durability. This arm is suitable for most track conditions, especially for medium- and high-traction tracks. Universal design allows this front arm to be used on either left or right sides.

Hard for Medium-High Traction tracks.  

Graphite for High-Mega High Traction Tracks.