I purchased these from a member a few days ago. We had plans to replace the heads and make them red/red for sale locally....the heads we have will not work.
I have five available.
$60 each shipped
passive is in reference to the power type; could be either ballast or passive; internally ballasts ones have a power supply as well as the flasher module to make them operate. passive ones dont need the power supply.
and to finish answering the question: it has an internal flasher, so no you wont need an external one