This is the Robinson Racing Hardened 29 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: 29 Tooth 48 Pitch Pinion Gear with 4mm Set Screw REQUIRES: 2mm hex wrench, GPMR8011 SPECS: Number of Teeth: 29 Pitch: 48 Hole Diameter: 5mm Outer Diameter: 0.64" (16.2mm) jxs 02/07/12 ir/jxs