This is the Robinson Racing Xtra Hard Steel 18-Tooth Pinion Gear with a 5mm shaft hole. This is perfect for use on the Traxxas Revo and E-Maxx when running electric motors with a 5mm shaft.
Includes: One 18 tooth pinion gear, One 4x4mm set screw
Requires: Installation onto the motor shaft
Specifications:Length: .48" (12.12mm)Mounting hole diameter: 5mm