Danisco has two major DVI lines for "American" cheeses, the RA, and the MA lines. They also have one in frozen pellet form, IIRC the 800 series
The RA lines come in two major variants, the ra 20-series, and the ra 70-series. They're very similar, but the 70-series work faster, have a faster pH curve.
The MA series are kind of the classic all-purpose acidifier. IMHO, the MA is best for not cheddar/jack/colby, but for farmstead cheeses like tommes. Or for fresher cheeses.
Havarti you could make with either RA or MA series.
Hope that helps.