This is the Center Differential Cup Outdrive for use on the MBX-5 buggy. FEATURES: Steel construction Silver in Color INCLUDES: Two Center Differential Cup Outdrives REQUIRES: Installation SPECS: Length- Cup: 15mm (.59") Overall: 29mm (1.41") Diameter- Cup: 11mm (.43") Shaft: 3.5mm (.13") JiM 11.18.08 ir/jxs