Utilising an airfoil effect for inducing cooling in a baseball cap, A.K.A. "Air Cap"

By adding a second smaller bill under the main bill of a baseball cap and creating a gap between the two bills, the upper bill creates a raised curve that acts like an airfoil and allows the free flow of air over a wearer's forehead, inducing a cooling effect. Besides the benefit of a cooling effect, the appearance of the hat is such that an observer looking at someone wearing it would not be able to tell there was anything overtly different about the design.