From what I gathered he was talking about the backup 4. Sorry about the 4s but I was posting from my iPhone and I made a lot of dumb typing mistakes.
I regret not asking further questions about the back up 4, because if wr get a legit backup then that means AK will be our 3 and cj will switch between backup 2 and 3. I assumed AK would be the backup 4, but I guess possibly not.