Cue sports playing nine-ball. Snooker balls are smaller than American-style pool balls with a diameter of 52.5 mm ( in), and come in sets of 22 (15 reds, 6 "", and a cue ball). English billiard balls are the same size as snooker balls and come in sets of three balls (two cue balls and a red, an object ball). Other games, such as bumper pool, have custom ball sets. Billiard balls have been made from many different materials since the start of the game, including clay, bakelite, celluloid, crystallite, ivory, plastic, steel and wood. The dominant material from 1627 until the
Rules of snooker by omitting the longest row of balls in the rack. Snooker balls, like the balls for all cue sports, are typically made of phenolic resin, and are smaller than American pool balls. Regulation snooker balls (which are specified in metric units) are nominally 52.5 mm (approximately inches) in diameter, though many sets are actually manufactured at 52.4 mm (about in.) No weight for the balls is specified in the rules, only that the weight of any two balls should not differ by more than 0.5g. Some recreational sets (which are usually not measured metrically) are in. (about 54 mm) up