Here is the Differential Ring and Pinion Gear become put on Traxxas Slash 4x4 automobiles. Features: metal construction Includes: One Differential Ring Gear One Differential Pinion Gear Specs: Pinion Gear: Enamel: 13T interior Diameter: 5mm (0.20") Ring Gear: enamel: 37T Internal Diameter: 6mm (0.24")