This is the optional MIP Drive Hub for use on the Traxxas E-Revo, Revo 3.3 #5308 & 5309, & T-Maxx 3.3 #4908. FEATURES: Steel construction Black in color INCLUDES: One 6mm Drive Hub Two 4x5mm Set Screws REQUIRES: Installation on the vehicle SPECS: Length: 19.5mm (0.77") Diameter: 12.75mm (0.50") cnh 5/27/09 ir/jxs