Handwritten post interview notes by the FBI agents.
Welllll the official 302 as submitted is not the immediate handwritten notes but an official memorandum sometime after the fact, so they are probably all typed and revised/edited. Normally they are supposed to be submitted withing days of the interview.
Submitting them SEVEN months later would be extremely sloppy at best, allowing all sorts of possible memory issues in what was supposed to be a contemporaneous record. But also, there is the obvious likelihood that this particular 302 has been sculpted to Strzok/McCabe purposes against Flynn. I think that has been indicated pretty specifically in all the stuff that came out from Strzok and Page.