This is the optional differential spool for the Traxxas Slash, Rustler, or Stampede truck. This is located in the gearbox and eliminates the differential. This part is recommended for off-road use only. FEATURES: stainless Steel Shaft CNC 6061 aluminum Light weight Gear Hub construction blue in color Hot Racing uses precision center-less grinding on these shafts to give you a degree of refinement which no other kind of operation can match and hardness for longevity. YOU WILL RECEIVE: One differential spool REQUIREMENTS: Assembly onto a Slash, Rustler, or Stampede.