The industry standard in wool fitted baseball caps. Official cap style of Major League Baseball and the National Association of Professional Baseball Leagues (minor league baseball umbrella organization), meaning that all caps worn on the field of play by MLB or non-independent league minor league clubs are 5950s.

The cap itself is made of six roughly equally-sized wool panels, with a wool-covered button at the top. The front two panels are reinforced with a mesh to support the shape of the front, where the logo is sewn on (often a stylized representation of the city's initial or initials). The bill is attached to the front two panels, but touches the adjoining two side panels as well.

At sweatband level at the meeting point of the two back panels on a play cap is a logo, either MLB (for major-league clubs) or the National Association (for minor-league clubs). Both logos are small, two-tone and rectangular; usually the dominant two colors of the cap, plus white for borders, will be used for the logo (rather than blue and red as in the official logos). On minor-league caps, and briefly on MLB caps at the start of the 2000 season, a small New Era logo was embroidered at center base of the left* side panel.

5950s are also manufactured for other sports for style purposes, but their primary use is in baseball.