This is the optional Robinson Racing Large Slipper Pad for use on the Traxxas T-Maxx, Revo 3.3, and the Slayer. FEATURES: High performance Fiber construction INCLUDES: One High Performance Large Slipper Pad REQUIRES: Installation on the vehicle SPECS: Outer Diameter: 39mm (1.5") Thickness: 3.4mm (0.13") cnh 4/6/09 ir/jxs