CALCULATING AT-4500 sets up in minutes - totals REGULAR and OVERTIME hours worked Calculates Regular and Overtime (Daily and/or Weekly) work hours Completely stand alone - no connection to PC required Quick and easy menu guided setup. No buttons to press or time card to align - employees simply drop in the card for punching AM/PM or 0-23 Hour format, regular (60's) or decimal (100's) calculated minutes Optional rounding rules and automatic lunch break deduction. Requires specific time cards http://www.amazon.com/gp/product/B01CKJN61S and ribbons https://www.amazon.com/dp/B01N7L795C.