This is the optional Two Speed Conversion Kit for the Traxxas E-Revo **This conversion kit requires a 3-channel transmitter to shift gears.** FEATURES: Everything needed to convert the E-Revo transmission to two speed shifting Provides more torque for climbing and driving through mud, grass and snow Close ratio first gear set provides almost seamless shifting into second for quicker acceleration Wide ratio first gear set provides the most extreme first gear ratio for maximum torque and low speed control INCLUDES: Wide and close ratio first gear sets, sub micro servo, linkage and instruction sheet REQUIRES: 3-channel transmitter, TRAL2225 Removing transmission from vehicle jxs 11/05/08 ir/jxs BOX DIMENSIONS: 5.13" W. X 1.75" H. X 8.38" L. BOX WEIGHT: .24 LBS.