This is the Robinson Racing Hardened 17 Tooth 48 Pitch Pinion Gear.
FEATURES: Constructed of hardened machined steel
May be used on motors with a 5mm shaft including Traxxas, Associated
and HPI models
INCLUDES: 17 Tooth 48 Pitch Pinion Gear with 4mm Set Screw
REQUIRES: 2mm hex wrench, GPMR8011
SPECS: Number of Teeth: 17
Pitch: 48
Hole Diameter: 5mm
Outer Diameter: 0.39" (10mm)