Known as the M-4 (the standard tin hat for ground troops is the M-I),the steel-and-leather skull cap weighs but two pounds, compares inlooks and comfort with the familiar football helmet.

"This is my favorite place to play," said Casinelli, wearing a black leather skull cap, black leather boots, a turquoise shirt and jeans. There's a story behind his snug skull cap.

As Smithsonian Mag notes, “in the early 1900s, soft leather skull caps appeared as optional headgear worn by few players. By the 1920s, hardened leather helmets were first worn, slightly ...