Abstract: A polypropylene bag for use in an automatic bag filling process including a sheet of polypropylene material formed as a tube having first and second sides or expanses sealed at one transverse end and open at the other transverse end to assume an unfilled, substantially flat profile wherein spaced-apart openings or notches are arranged on the transverse open edge portion of the first expanse. In a bag filling process, horizontally stacked bags are arranged on a bag opening unit and two projecting tabs or fingers of a clamping device are inserted through the notches of the uppermost stacked bag for contact against the second or lower side. A partial vacuum producing device applies suction to the upper or first surface and pulls same upwardly. The fingers maintain the lower side substantially flat. The bag is then fully opened and positioning arms of the unit are inserted into the bag which move it into a vertical position for placement under a filling spout.