This is the Castle Creations 13T Mod-1 Pinion Gear for use on 1/8 Scale Cars. FEATURES: Steel construction Black in color YOU WILL RECEIVE: One 13T Mod-1 Pinion Gear One 3x4mm Set Screw REQUIREMENTS: Installation on the vehicle SPECIFICATIONS: Length: 12mm (0.47") Inner Diameter: 5mm (0.20") lmm 04.08.10 ir/jxs &