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
Snooker its spot as a tiebreaker. A player may also concede a frame while on strike if he or she thinks there are not enough points available on the table to beat the opponent's score. In professional snooker this is a common occurrence. Points may also be scored in a game when a player's opponent . A foul can occur for various reasons, most commonly for failing to hit the correct ball (e.g. hitting a colour first when the player was attempting to hit a red), or for sending the cue ball into a pocket. The former may occur when the