This is the Hard Aluminum 48P 43T Pro Pinion Gear from Robinson Racing.                                                                                     FEATURES: Hard aluminum construction                                                              Black in color                                                                          43 Tooth                                                                                48 Pitch                                                                                                                                              INCLUDES: One 48P 43T Pinion Gear                                                                  One 3x3mm Set Screw                                                                                                                                   REQUIRES: Installation on the Motor Shaft                                                                                                                       SPECS:    Outer Diameter: 21.65mm (0.85")                                                      Inner Diameter: 3.15mm (0.12")