Accessories:Rear Knuckle Arm -2pcsStainless Steel Cap Head Screw 2.5x14-8pcsOriginal Name / Part No:LOS242052Part location:Rear knuckle armDoes this product replace a specific part or function?yesProduct major function & usage:stabilize rear axle and bearingMajor advantages of upgrading to this product:1. Aluminum 6061 T6 is light material with high tensile strength for great durability during extreme RC action.3. Precise bearing position minimizes the gap so the rear wheel joints can rotate smoothly, making the wheel more stable.