Fermaid O is a newer formulation of the same Fermaid K that winemakers everywhere have learned to trust their ferments to. The main difference in composition between the two, is that the Fermaid O has replaced the inorganic DAP with an organic source. In terms of how this benefits the winemaker, there are several points!
This is a nutrient which will boost the quality of wine, regardless of process. Lower heat production, less negative flavor compounds, better overall fermentation kinetics and flavors!
Use at a rate of 1.5g / gal of must/juice.