Section 2: Equipment
2.1 The Baseball (OBR Rule 3.01)
Per OBR Rule 3.01, the baseball must be a sphere formed by yarn wound around a small core of cork, rubber, or similar material, covered with two stripes of white horsehide or cowhide, tightly stitched together. Official specifications:
- Weight: Not less than 5 nor more than 5¼ ounces avoirdupois (141.75–148.83 grams)
- Circumference: Not less than 9 nor more than 9¼ inches (22.86–23.49 cm)
- The home club shall have available for use during a game at least three dozen regulation baseballs.
- Each ball shall be presented to the umpire-in-chief at least 2 hours before game time.
2.2 The Bat (OBR Rule 3.02)
Per OBR Rule 3.02(a), the bat shall be a smooth, round stick not more than 2¾ inches (6.985 cm) in diameter at the thickest part and not more than 42 inches (106.68 cm) in length. The bat shall be one piece of solid wood, or formed from a block of wood consisting of two or more pieces of wood bonded together with an adhesive in a manner approved by the Commissioner.
- Cupped bats (Rule 3.02(b)): An indentation in the end of the bat up to 1 inch (2.54 cm) in depth is permitted, so long as it is no wider than 2 inches (5.08 cm) and no less than 1 inch (2.54 cm) in diameter.
- Pine tar restriction (Rule 3.02(c)): The bat handle may be covered with any material or substance to improve the player's grip, but such material or substance shall not extend more than 18 inches (45.72 cm) from the bottom of the handle. Violation results in the bat being removed from play; no out or other penalty is imposed on the batter.
- Bats that are discolored, laminated, or experimentally treated in a manner not approved by the Commissioner are prohibited.
2.3 Gloves and Mitts (OBR Rule 3.05–3.07)
All fielders, with the exception of the first baseman and catcher, may use a glove or mitt of any weight. OBR Rule 3.05 specifies size limits:
- Fielder's glove: Not more than 12 inches (30.48 cm) measured from the tip of any finger to the bottom of the glove, and not more than 7¾ inches (19.685 cm) wide across the palm.
- First baseman's mitt (Rule 3.06): Not more than 12 inches (30.48 cm) from top to bottom and not more than 8 inches (20.32 cm) wide across the face.
- Catcher's mitt (Rule 3.07): Not more than 38 inches (96.52 cm) in circumference and not more than 15½ inches (39.37 cm) in height.
- Pitcher's glove: The pitcher's glove, including the lacing and any webbing, shall be a uniform solid color. The color white or gray is not permitted for the pitcher's glove (Rule 3.05(c)).
2.4 Helmets and Protective Equipment (OBR Rule 3.09)
Per OBR Rule 3.09, batters must wear a protective helmet while at bat, while running the bases, and while in the on-deck circle. Helmets must carry the official approval mark of the Commissioner and must have at least one ear flap (facing the pitcher). Catchers must wear a catcher's helmet and mask, chest protector, and shin guards during all games. As of the 2023 season, MLB mandates two-ear-flap helmets for all position players in certain situations, and continues to phase in enhanced concussion-protection requirements.
2.5 Uniforms (OBR Rule 3.03)
Per OBR Rule 3.03(a), all players on a team shall wear uniforms identical in color, trim, and style. Shoes with pointed spikes similar to track or golf shoes are prohibited (Rule 3.03(b)). No player may wear a uniform bearing the number of a player on the opposing team's active roster.