【54T Motor Gear】0.8 metric pitch; compatible with 32-pitch, motor gear diameter: 45mm/1.77inch; inner diameter: 11.9mm/0,47inch, replace for 3956 | 【15T/17T/19T pinions】Inner diameter: 5.0mm/0.196inch, come with a 3.175mm coupler to convert 3 pinions apertures to 3.175mm/0.125inch. Suitble for 5mm and 3.175mm shaft motors | 【Application】The gear kits compatible with Traxxas Slash 4x4 4WD/2WD/VXL R