This is the ST Racing Concepts Blue Aluminum Oversized Rear Hub Carrier w/Bearings. Using high quality CNC machined aluminum, these oversized Aluminum rear hub carrier greatly increase the strength of your rear suspension, while adding great looks to your Traxxas electric Stampede, Rustler, Bandit or Slash. Because of the increase in size of bearing for durability, we have included a full set of 5x11mm ball bearings (replacing the stock 5x9mm bushing) for improved efficiency of the rotating axle and durability.