Well, Swans Down is just a well-known and popular brand of cake flour in the U.S.. Can you get any brand of cake or pastry flour? Any brand will do just as well. Cake or pastry flour is fine textured flour made from "soft" wheat with a high starch content.

In recipes, you can substitute 1 cup less two tablespoons of sifted all-purpose flour for 1 cup of sifted cake flour.