I compared this yeast to a popular brand of jarred, bread machine yeast. This yeast gets an "A" while the other yeast gets an "F" (which coincidentally is the starting letter of its name.) The "F" yeast did not last a month, even though it was stored properly. Within 4 weeks, it had lost its potency and failed to make decent bread. Meanwhile, this 2 lb bag of Red Star, kept in a sealed plastic tub in the freezer, has worked for months on end.