【Preset Rules Printed on the Back】- 42 preset rules printed on the back of the digital chess clock, ready to use; default values can be changed and saved internally for reuse. 【Parameter Record Retention】- Chess timer switches off and then switches back on, retaining the rules and parameters of the game before switching off. 【Functions】- The Chess Clock Timer features 42 timing rules in 8 categories, including single/multiple countdown, bonus, time limit, time delay, seconds and forward. Timing parameters can be changed for each timing rule (except forward timing). 【Portable Battery Power】- The Chess and Game Timer is powered by a DC 3V power supply (two #5 batteries not included). Compact size, can be used on the go, enjoy the game anytime and anywhere. 【Large See-Saw Button】- The portable timer is designed with large see-saw buttons that are tactile, responsive and easy to control, making it more suitable for rapid chess.