This is the 77T 48P Spur Gear for the HPI Blitz. Nylon construction Black in color One 77T 48P spur gear Installation on vehicle SPEC: Outer Diameter: 42mm (1.65") Inner Diameter: 13.5mm (0.53") Thickness: 5mm (0.20") Teeth: 77 Pitch: 48 lmm 7.16.10 ir/jxs &