a hanger system hangs flexible plastic bags by an increased thickness of plastic near the tops of the bags . the bags &# 39 ; increased thickness results from ridges of slightly thicker plastic wall at the top of the bag , such as is common to rib and groove bag closures . bags are supported downhanging from slots defined between adjacent rails , or fingers . the width of the slot is normally such as to maintain a downhanging bag securely closed , but may be widened over a short region . the seal of the bag may be opened at this widened region and material , particularly liquids and gases , may be inserted into or extracted from the cavity of the downhanging bag , particularly by use of a tube , or straw .