HPI Brake Linkage Set for the HPI Nitro RS4, RS4 2, Super Nitro RS4, Nitro Rush and RS4 RTR Kits.This Linkage Set connects to the throttle servo and controls the speed of the engine and brake application. Replaces bent or missing linkage components. This kit includes one brake linkage set for the HPI Nitro RS4, RS4 2, Super Nitro RS4, Nitro Rush and RS4 RTR Kits. One A890b brake arm. One A896 Throttle Linkage. One A890a 2mm x 100mm Brake Rod. One A050 0.8mm Front Spring. "