Fermax Yeast Nutrient:
diammonium phosphate (DAP),
dipotassium phosphate,
magnesium sulfate,
and autolyzed yeast
Fermaid® K
ammonia salts (DAP),
sterols,
unsaturated fatty acids,
key nutrients (magnesium sulfate, thiamin, folic acid, niacin, biotin, calcium pan*tothenate),
free amino acids (organic nitrogen derived from inactivated yeast),
and inactive yeast.
Seems like Fermaid has a few more nutrients than Fermax.
I believe the most important nutrient is DAP (which I believe is bad during rehydration). I'm guessing that kits have more than enough of the other stuff.