【Compatible with】(5mm) Shaft Size Motors,make sure your RC motor shaft have the same diameter. Compatible with Arrma Traxxas Axial HSP Redcat Losi 1/8 1/10 scale rc car truck buggy. 【Material】Made of Quality Hardened Steel to increased wear resistance and improve fatigue life,make them roll smoothly. 【Package】Mod 1 / 12T 14T 16T 18T 20T pinion gear sets and a hex key 【Note】The variety of tooth pinions allows for more gear setups, for different racing track conditions. To avoid the ESC/motor overheat, please check the ESC and motor temperatures regularly throughout the run after change the pinion gear. 5pcs Mod 1 Pinion Gear 5mm Set Hardened Steel 12T 14T 16T 18T 20T fit 5mm RC Motor Shaft M1 Pitch Gears Compatible with Arrma Traxxas Axial HSP Redcat Losi RC Car Truck Buggy (with Screwdriver)