FAST Automatic Transmission Control Solenoid Bump Stager Module for XFIAvailable as a complete kit, the Bump Stager lets drag racers carefully pulse the transbrake. This enables the vehicle to move forward slowly during staging, creating a higher degree of repeatability than racers are able to achieve manually. The complete kit comes with everything needed for use in the box, and a built in 20 amp driver removes the hassle of wiring an external relay for most applications.