The Redline Crank Trigger kit is a precision timing device that allows for the most accurate timing adjustment. The kit will fit all 302 /351 based HO dampers. Initially designed for use with the Holley EFI, but if used with the optional Holley Hall Effect sensor #554-124, it can be utilized to work with any EFI system. The wheel and all hardware is included. The Holley sensor #554-124 (shown in photo) sold separately.