WOODEN TRIANGLE RACK FOR 2 1/4 INCHES BILLIARD BALL-BRANDNEWA rack (sometimes called a triangle) is a piece of equipment that is used to place billiard balls in their starting positions at the beginning of a pocket billiards game. Rack may also be used as a verb to describe the act of setting billiard balls in their starting positions (e.g. "to rack the balls"), or as a noun to describe a set of balls that are in their starting positions