Universals in travel. The men's driving cap. See it here at Vlad's castle ruin in Romania, worn by The Guide.
Many of us know little of the stitcheries of driving caps vs. newsboys' caps, and other similar caps around the world. The fashion is global because it is practical, the cap is easy to carry, stays on, and looks good.
Style details. We understand this about details: the well-designed and well-fitting cap accommodates base of skull to hairline, no puckering. It should be stitched (not snapped) at the front (we do not recall here). There should be three panels to be a driving cap, and more like eight for the more circular, wider newsboy's cap. Think of the 1930's - kids on the streets hawking papers.
Sometimes there is a buckle in the back. The longer the brim in front, the tougher the look. This fine guide, who lives near the ruin, was gentle and had a welcoming cap.
Measuring for a driving cap. What is your size? For a European cap, measure your head, say in inches for Americans, then multiply that times 2.54; or, for an American cap, divide by 3.14 or pi.