The Drag Coefficient of an object multiplied by its cross sectional area. This is used to scale the drag value for a particular object from the dimensionless Cd. Theoretically, every object of a similar shape will have the same Cd regardless of its size, meaning that both a grain of rice and a Zeppelin would be the same. Multiplying by the area allows comparisons of the true drag between dissimilar objects. For example, the original Honda Civic had a horrible Cd, and makers of large luxury cars, with a little edge rounding, were easily able to beat it and proclaim "Lower drag than a Honda Civic!" in their ads. This is patently absurd as the Honda had such a tiny cross section, thus much lower *actual* drag. See also Optimum Mass