Sudoku 15K The Ultimate Numerical Challenge! eSudoku Non-Slip Key Pad, Up to 15,000 Variations, LCD Screen Timer, Record of Fastest Solution Time, Replay Mode, Low Battery LED Indicator Storage Pouch, Battery Back-Up for Memory, Last Puzzle Recall, Sound Effect, Auto Shut-Off Two (2) Levels of Play - Beginner/Expert Three (3) Levels of Difficulty - Easy/Intermediate/Hard