Extreme heavy-duty rear steel CV (constant velocity) driveshafts feature larger 6 mm stub axles to work specifically with the Extreme Heavy Duty Upgrade Kit. Designed for intense high-power applications, these shafts are built to withstand the brutal torque from the 540XL motor and the massive grip of huge Sledgehammer® tires. Traxxas’ unique, splined telescoping design delivers full-range articulation, so there is never a need to limit suspension travel. Since they are made by Traxxas, you can count on easy installation and perfect fit in your Traxxas model.