If you bouth the basic or Reverse harness from GJ Motorsports and want to add flashing patterns to your rear amber lights this it the add on kit for you.   It comes with the flasher and diodes to allow you to use one switch for solid or a second swith for flashing lights.   This works great for those of us who have to stop on the site of the road for work or while on constrution sites when not offroading.   This also works great for regular F-150 or Super Duty trucks while plowing and want to use flashing ambers for additional warning lights.