To speed up match play and to add an additional element of strategy, a doubling cube is included in most quality backgammon sets. The doubling cube is never rolled during play. It is used as a marker with the numbers 2, 4, 8, 16, 32, and 64 inscribed on its faces. The number denotes the current stake in the game. At the start of each game, the doubling cube is placed on the bar with the number 64 showing. At this point, the stake is effectively one. During play, the player about to roll may propose that the game be played for twice the current stakes by turning the doubling cube so that the number 2 is showing. Their opponent must either accept the doubled stakes or resign the game immediately.
The doubling cube was introduced in the 1920s by an unknown player. The added dimension of strategy has been popular ever since. As the doubling cube is merely a marker there is no requirement for it to be manufactured to precision standards. A doubling cube will come standard with most backgammon dice sets. However, many backgammon sets made in Greece will not include the doubling cube or dice cups. This is because the local game of tavli has slightly different rules.