This is the 21 Tooth M5 Pinion Gear from Tekno RC. FEATURES: Ideal for 1/8 scale and other MOD1 pinion applications Constructed of CNC machined steel, lightened and hardened for durability Standard length shank Number of teeth laser etched on shaft INCLUDES: 21 Tooth Pinion Gear, M5 Set Screw REQUIRES: Installing on motor shaft and securing with set screw SPECS: Number of Teeth: 21 Gear Pitch: MOD1 Hole Diameter (Bore): 5mm jxs 10/24/11 ir/jxs