A rounded, solid wooden or hollow aluminum bat. Wooden bats are traditionally made from ash wood, though maple and bamboo is also sometimes used. Aluminum bats are not permitted in professional leagues, but are frequently used in amateur leagues. Composite bats are also available, essentially wooden bats with a metal rod inside. Bamboo bats are also becoming popular.
The fungo is used by a coach to hit balls for defense practice. It is lighter weight, so less fatiguing to hit ball after ball. The fungo sheds its weight above the hands. The severely tapered barrel to drops weight and maintains a high moment of inertia. While the bat would be at greater risk of breaking if used in a live batting exercise, it is safe to use in practice because there are much fewer mis-hits.
Within league standards there is ample latitude for individual variation, many batters settling on their own bat profile, or one used by a successful batter. Formerly, bats were hand-turned from a template with precise calibration points; today they are machine-turned to a fixed metal template. Historically significant templates may be kept in a bat manufacturers' vault; for example, Babe Ruth's template, which became popular among major-league players, is R43 in the Louisville Slugger archives.