Why do I need PostFix adapter to RGH Corona V2...

Hi y'all. I research alot but I didn't find anything on it...here is my question...wath the post fix adapter actualy do ? Wath is post out...And do I need to leave it on the console after RGHing ?

I know that I have a V2 and I know that I haven't post_out...

I need :
- glitch chip (I'll buy x360ace v3 because its the cheapest)
- r/w sd card adapter (I'll buy one that fit on v4 and v6 too)
- postfix adapter (that I don't know wath it is...)

Thanks guys !