a flexible , thin wall , multi - layer plastic film pouch having an open end and possessing high strength resistance against being manually torn or stretched . a portion of the pouch , extending to the open end , projects upwardly through a substantially rigid annular flange . the end portion , being mechanically stretched outwardly and downwardly over the annular flange , fits tightly over , around and beneath the flange . the pouch is secured to the flange without further means of attachment . thus , with the pouch being secured to the flange , the end portion provides the pouch with a substantially rigid brimmed annular opening that facilitates storage , aggressive handling and use of existing filling and closure equipment for filling and closure of the pouch .