Put an end to recoil starter headaches and add one-hand starting ease by installing the Kwik-Pit Super Start System from DuraTrax on your model. This version will convert recoil or EZ-Start equipped Traxxas Brand TRX 2.5 engines to the Super Start System. FEATURES: Easy one-hand starting means the end of blisters and broken recoil ropes . Powerful twin 540 motors are powered by twin 6-cell sub-C stick battery packs (not included) Unit will not operate on only one pack Steel gear drive. Dust and impact resistant composite plastic case . Hinged access door provides for easy battery installation . ON/OFF rocker switch with safety side guards . Twin ball bearing supported gear drive. Two clips on the unit's bottom for storage of starting shaft . INCLUDES: One Kwik-Pit Super Start power unit . One front and rear gear case - key number 19. One 32 tooth steel, adapter gear - key number 18 (DTXP6051). One 11 tooth steel, small adapter gear - key number 12 (DTXP6045). Three 3x12mm hex head screws - key number 26 (DTXQ0285) (requires a 2.5mm allen wrench for installation - DTXR0254). Two 2.6x8mm hex head screws - key number 16 (DTXQ0283) (requires a 2mm allen wrench for installation - DTXR0252) . REQUIRES: The stock engine back plate and one way bearing . Two 6-cell sub-C batteries and charger - DTXP4600 or modeler's choice Installation following included instructions sheet.