Hello gentlemen, I believe that Miller makes a bunch of the inverter machines that Red-d-Arc has their sheet metal put onto. I also seem to recall that many of their engine driven machines are based on a similar scenario using the Lincoln chassis. You should be able to get any of the add-on features for these machines that would be available through Miller or Lincoln for their regular line. I don't believe that Red-d-Arc builds any of their own machines. There should be an internal module that can be added onto the machine to give it CV capability, as far as high frequency goes, makeithot is correct in saying that it requires an external unit, I believe. Just my $.02. Regards, aevald