Big marbles, ones that are larger than the standard size marble, are called "shooters." A big marble is also known as the offensive marble. The big marble gleans these names because it is the one shot at other marbles in an offensive manner.
The standard size of a shooter in the United States and Western Europe is 3/4 inch. In other parts of the world, the shooter is 1 inch in diameter. Occasionally, a shooter is smaller in size, but no less than 1/2 inch. The ultimate purpose of a shooter is to knock a target marble out of the ring.