54T motor main gear comes with 16T/18T/20T/21T pinions and 3.175mm coupler.Four pinions is 5mm, Using the coupler can convert Four pinion apertures to 3.175mm.so this product for motors with 5mm or 3.175mm shaft diameter.3660 3670 3674 4274 4268 550 540 3650 etc series motors.54T main gear replace 3956.0.8 metric pitch; compatible with 32-pitch; pinion sinner diameter: 5.0mm/0.196inch; main motor gear dia.: 45mm/1.77inch;inner diameter: 11.9mm/0,47inch.compatible with Traxxas Slash 4WD/2WD/VXL Rally/Stampede VXL /Traxxas 1/10 Summit/Trxxas 1/10 E-/T-Maxx/Jato/ VXL/Summit/T-Maxx.All metal internal gears for strength.Made of heavy duty hardened steel, long time life span.The speed depends on your gear ration. We provide four different teeth pinion gear to make you more choice in gear ration.Colour: blackMaterial: metalPackage Contents:1 * 54T Gear1 * 16T Pinion1 * 18T Pinion1 * 20T Pinion1 * 21T Pinion4 * ScrewsOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.