This is a 31 Tooth, 48 Pitch Pinion Gear with Set Screw from Traxxas. FEATURES: Steel construction, silver in color INCLUDES: One 31 Tooth, 48 Pitch Pinion Gear One 3x4mm Set Screw (1.5mm hex size) REQUIRES: Installation SPECS: Length: .42" (10.5mm) Inside Diameter: 1/8" Outside Diameter: .69" (17.5mm) kpm02/05/2008 ir/jxs