A word used to define an "F-2", "F-3", or "F-4" STAR CASE Rackmount case. An "F-4" is a rack shell packaged within a front and rear removable lid outer case. Two inches of foam isolate the inner shell from the outside case. "F-2" style differs only in the fact that it has 1" of foam isolation instead of 2" and removable "B-3" or "B-4" style outer case.