This is the 1st Speed Gear for the Traxxas Revo. FEATURES: Nylon construction INCLUDES: One 1st speed gear REQUIRES: Assembly to vehicle If the Primary Shaft Set is needed, use TRAC5393. SPECS: Gear Diameter: 45mm (1.7") Gear Thickness: 5.5mm (.22") Teeth Count: 43 teeth COMMENTS: If the Primary Clutch Assembly is needed, use TRAC5390.