These are Inner Drive Cups for the Traxxas Revo/T-Maxx. FEATURES: Steel construction INCLUDES: Two steel constant velocity driveshafts Two M4/15 screw pins REQUIRES: Installation onto vehicle. SPECS: Length: 18mm (.70") Diameter: 13mm (.51") tlw 6/6/07 ir/jxs BOX DIMENSIONS: 3.25" W. X .50" H. X 4.00" L. BOX WEIGHT: .06 LBS.