Here is the optional Tamiya Aluminum Horn for Hi-Torque Servo Savers. Features Tamiya 54121 Aluminum Horn/High Torque Servo Saver Usable on TB-03, TA05, DB01, DF-03, TRF501X, TRF416 and TRF415 Chassis Aluminum construction Anodized blue in color Contents Aluminum Horn for Hi-Torque Servo Savers with instruction sheet