Players and Their Equipment
All players on a team use the same basic equipment: They wear uniforms, caps and shoes with rubber cleats or metal spikes. On defense, fielders use a leather glove designed for catching balls. Rules determine the size of the glove and the construction of the webbing between the thumb and first finger.
Because they have to catch more balls than other fielders, catchers and first basemen have extra-large gloves, or mitts. Catchers' mitts have extra padding and cannot be more than 38 inches (96.52 centimeters) in circumference or more than 15 1/2 (39.37 centimeters) inches from top to bottom. First baseman's mitts can't be more than 12 inches (30.5 centimeters) from top to bottom and 8 inches (20.3 centimeters) across the palm. The space between the thumb and finger sections of the mitt can't be more than four inches (10.2 centimeters) across at the top [source: Major League Baseball].
Catchers wear special protective equipment including a facemask, chest protector and shin guards.
On offense, players wear batting helmets for safety and batting gloves to improve their grip. Bats in Major League Baseball are made of one piece of solid wood, not more than 42 inches long (107 centimeters) or 2 3/4 inches (6.985 centimeters) in diameter [source: Major League Baseball]. In most other leagues, bats are made of aluminum.