The digital chess clock models featured in the Bonus-Only category differ from the models in the Entry Level category by offering a count-down game mode for one time period with bonus (Fischer increment) capability. The models in this category do not offer count-up functionality, nor do they include the delay functionality of the models in the higher Bonus-Delay category.
With bonus options activated for these models both players are allocated an amount of extra time before each move, configurable for one time period. This concept, envisaged by the late world champion Bobby Fischer, helps to minimise time scrambles marring competitive play.
Models in this category are suitable either for players requiring bonus capability for a single time period or for those who while not having such a need now, are attracted to the potential flexibility for only a small premium over an otherwise equivalent Entry Level category model.