These are the 12mm Hex Adapters from Traxxas.                                                                                                 FEATURES: Allows XO-1 Supercar type steel-splined driveshafts with 6mm axles to            be used on the 1/10 scale Traxxas Slash 4x4, Rally 4x4, and                    Stampede 4x4                                                                 Heavy duty machined aluminum construction, blue in color                       Compatible with Traxxas short course and rally wheels, and most 12mm             hex style wheels                                                                                                                                  INCLUDES: Four 12mm Hex Adapters, 6mm Drill Bit, Screw Pins, and Instructions                                                                                 REQUIRES: Two #6451 XO-1 Front Driveshafts, TRAC6451                                     Two #6452 XO-1 rear Driveshafts, TRAC6452                                      One #6439 XO-1 Left and Right Steering Blocks, TRAC6439                        One #6455 XO-1 Left and Right Axle Carriers, TRAC6455                          Three #5117 6x12mm Ball Bearing Sets, TRAC5117