I know what the MP3 is but whats the BK (rr3%)?

# mp3 V0 + BK (rr3%)

Booklet (Recovery record 3%)

EDIT:
The latter may be useful if you end up with corrupted files, because it allows you to repair the archive (well, try, at least).

such a low RR... dose that mean it most likley won't work?

That depends on the level of corruption. You only need the recovery record if the archive is corrupted. If the file is intact, you don't have a problem.

most times, if download corrupted, only small pieces corrupt, so 1-3% recovery will allow repairing full without download all over again.