AC/DC "For Those About To Rock" vintage backpatch (silver version).
It comes from a private collection with documented material dating strictly from 1981 to 1986. It may be a bootleg, but AFAIK AC/DC representatives started to copyright patches from "Fly On The Wall" only (please correct me if I'm wrong), so it might be official as well. I was notably produced as an alt. version with golden flakes instead of the silver ones present here.
It's in a quite good condition for its age.