This is the 54T Fine Pitch 2nd Gear for the Mugen MTX4-R Chassis Kit. FEATURES: Nylon construction Black in color Fine Pitch INCLUDES: One 54 Tooth Fine Pitch 2nd Gear REQUIRES: Installation on vehicle SPECS: Inner Diameter: 15mm (0.59") Outer Diameter: 44mm (1.73") MugenPart MUGT0284