BL-RS4 Drift Spec A combo set that combines a speed controller and a ZERO-S drift spec motor.The RS4 speed controller with well-balanced performance is equipped with a drift-only program as standard, and has acquired an expert-level start setting. Of course, it has powerful basic performance, and it is possible to bring out further performance by combining it with a dedicated programmer (BL-YBP4) or Wi-fi module. Excellent compatibility with the YD-2 series chassis in combination with the color alumite ZERO-S motor. You will have a machine with clear total coordination.