This is the optional Heavy-Duty Servo Saver Spring for the Traxxas Revo. FEATURES: Steel construction Chrome Plated Conical Shape INCLUDES: One Heavy-Duty Servo Saver Spring REQUIRES: None SPECS: Small Diameter: 12mm (.472") Large Diameter: 22mm (.866") Static Height: 14mm (.551") Diameter of wire: 3mm (.118") COMMENTS: If the Upper & Lower Steering Arms are needed, use TRAC5344.