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
Power Snooker Professional Billiards and Snooker Association, organisers of the World Snooker Championship and other ranking tournaments, and regulators of the professional game. The format has however been officially sanctioned by the WPBSA's chief shareholder, Barry Hearn. Simons has stated that he sees Power Snooker as simply another format of the game, it being one of many new experimental formats and several new tournaments introduced since Hearn took control of World Snooker, rather than a threat to the established format of the traditional game or a competitor to WPBSA tournaments. Power Snooker advertises itself as part of the World Snooker Calendar of