The DF-999Ac Automatic Folder has a high speed of up to 260 sheets per minute, and utilizes a patented three-roller friction feed system to process a wide range of paper stocks. The delivery rollers automatically set paper size, and there are two tray positions available for enhanced stacking. The DF-999Ac offers double document detection which reads the thickness of paper and will detect when more than one sheet of paper is fed into the machine at a time. The ultrasonic sensor will automatically pause the machine when it detects a double feed.