This is a 21 Tooth 32 Pitch Pinion Gear for the Traxxas E-Maxx Truck.  This is the gear which is attached directly to the motor.                                                                                            FEATURES: Machined Steel                                                                          Designed for a 3mm shaft                                                                                                                              INCLUDES: One 21 tooth Pinion Gear                                                                One 3 x 4mm Set Screw                                                                                                                                 REQUIRES: Assembly onto an E-Maxx truck.                                                          1.5mm hex wrench to tighten set screw.                                                                                                                COMMENTS: This gear is only one of two which are used on the E-Maxx dual motor  set-up.