Summer flat caps or summer caps are a type of hat with a round, flat top and a small brim that extends down the front and back. For summer use, flat caps are often made of cotton or silk, in some cases mixed with artificial fibers for extra durability, but wool is also fine for a summer hat - ideally without a lining. Flat sixpence caps are also sometimes called news boys or ivy caps - we have types such as gatsby which are variations on the same theme.