These are optional Aluminum Rear "H" Arms (Weight Spec/Short) (Black) for the Yokomo RD2.0/SD2.0
This optional part combines an aluminum rear H-arm with a brass weight to systematically increase rear traction. By mounting the weight on the rigid aluminum H-arm, the unsprung weight, which is directly loaded on the rear tires, is increased, effectively increasing tire traction. Unlike increasing the chassis weight, the weight is applied regardless of the pitching motion, so the slide is well controlled even when entering a corner, and a sense of stability is maintained. By adding an additional 5g or 10g weight to the base 20g weight, the amount of load applied can be controlled.