Solid Color Caps -
The Brooklyn style, wool baseball cap, descending from the Jockey cap (a French version is seen in the circle on the painter Edgar Degas circa 1880), while occurring in the late 19th century baseball- especially at universities, began to replace the Chicago style box cap soon after 1900. Its distinctive feature was the short, flexible visor. By 1920 it was the dominant style ball cap. Thereafter the visor length increased, synthetic fabrics were introduced and the crown squared up on the road to the modern ball cap.
A standard early 20th century round, soft-crown, wool flannel cap. Inside, is a horsehair front backing and leather sweat band. The 2” visor is flexible so that it folds in your pocket and has a dark green wool flannel under visor.