Celltrac's Key benefits: Worlds only ergonomic keyboard layout - Easier to locate keys Very soft touch keys - Helps prevent finger fatigue Battery or Mains power supply - Ultimate portability Half the cost of comparable desktop models 12 Counting keys (10 Summing 2 non summing) Subtract following an error Add or subtract cell clusters Display current cell total and running totals at any point during the count Bleeps a warning when approaching 100 cells, or multiples, Total counts can be reported in absolute numbers or percentages Maximum count = 999