This is an optional Traxxas Rear Steel Constant-Velocity Driveshaft Set, and is intended for use with the Traxxas Slash 4X4 and Slash 2wd 1/10 scale short course trucks, as well as the Traxxas Rally. Traxxas Steel Constant Velocity Shafts offer the ultimate in torque handling and efficient power transfer. The outer U-joints are lubricated and sealed by a rubber boot for maximum protection against the elements, and the U-joint pins are held captive so you never have to worry about losing a pin. Gleaming nickel-plated shafts and blue silicone boots add a custom look.