What does .39 @ 3 bars or .34 @ 90 P.S.I mean on a campbell hausfeld air compressor?.?

I live in Trinidad and Tobago, and the Air Compressors are very limited, I know that you go with e.g. 10.2 Cfm @ 90 P.S.I. or 11.5 Cfm @ 40 P.S.I. I am looking to buy a 60Gal Air Compressor but Is single better or Two Stage? But I don't know how to calculate .39. Cfm @ 3 Bars.
I don't know what category to place this in so plz help trying to buy one soon!

2011-09-16T20:21:32Z

Ok what I am trying to ask is what does the .33 mean in cfm???

ClassicMustang2011-09-15T19:37:54Z

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I found this answer...
http://answers.yahoo.com/question/index?qid=20110511095355AAdp4df

1 bar = 14.5 psi app