This is the optional 23 Tooth 48 Pitch Pinion Gear for the HPI Switch On-Road Car. FEATURES: Constructed of steel INCLUDES: 23 Tooth 48 Pitch Pinion Gear REQUIRES: Installing on motor shaft and tightening set screw SPECS: Diameter of Hole: 1/8" (3mm) Number of Teeth: 23 Pitch: 48 jxs 06/01/11 ir/jxs