An article of manufacture comprising: a.) a bag comprising: i.) a front surface; ii.) a rear surface; iii.) two side surfaces each having a gusset therein and connecting said front and said rear surfaces (12, 14); iv.) a flattenable bottom surface formed by connecting said front, said rear, and said side surfaces (12, 14, 18), the gussets of the two side surfaces being sealed at the bottom surface with a K-seal; and v.) a top surface formable by connecting said front, said rear, and said side surfaces (12, 14, 18); said bag having a height, a width, and a depth, and an internal volume; vi.) a non-reusable closure; wherein said non-reusable closure has a length that extends along said width of said bag, wherein said non-reusable closure comprises a membrane connectable between said front surface and said rear surface of said bag, said membrane having a user-facing surface, an outer surface, and a tear strength of at least 1 kg/cm 2 (15 pounds per square inch); wherein said bag is sealable and has a seal strength of at least 112 kg/cm 2 (1,600 pounds per square inch); and wherein said bag comprises a plastic laminate having a thickness of from 130 to 200 microns and a tensile strength of at least 239 kg/cm 2 (3,400 pounds per square inch); and b.) at least about 6.8 kg (15 pounds) of a particulate, flowable composition contained therein; the bag being characterized in that the membrane is a co-extruded blend of ethylene-derived polymer selected from the group consisting of low density polyethylene, high density polyethylene, ultra-low density polyethylene, and combinations thereof, and in that a plurality of ribs (36a, 36b) is arranged on the outer surface of the membrane, such that a portion of said outer surface of the membrane is sealable to an inner surface of the front surface of the bag and a portion of said outer surface of said membrane is sealable to an inner surface of the rear surface of the bag, with the ribs (36a, 36b) being formed from ultra low/very low density polyethylene. a.) a bag comprising: i.) a front surface; ii.) a rear surface; iii.) two side surfaces each having a gusset therein and connecting said front and said rear surfaces (12, 14); iv.) a flattenable bottom surface formed by connecting said front, said rear, and said side surfaces (12, 14, 18), the gussets of the two side surfaces being sealed at the bottom surface with a K-seal; and v.) a top surface formable by connecting said front, said rear, and said side surfaces (12, 14, 18); said bag having a height, a width, and a depth, and an internal volume; vi.) a non-reusable closure; wherein said non-reusable closure has a length that extends along said width of said bag, wherein said non-reusable closure comprises a membrane connectable between said front surface and said rear surface of said bag, said membrane having a user-facing surface, an outer surface, and a tear strength of at least 1 kg/cm 2 (15 pounds per square inch); wherein said bag is sealable and has a seal strength of at least 112 kg/cm 2 (1,600 pounds per square inch); and wherein said bag comprises a plastic laminate having a thickness of from 130 to 200 microns and a tensile strength of at least 239 kg/cm 2 (3,400 pounds per square inch); and i.) a front surface; ii.) a rear surface; iii.) two side surfaces each having a gusset therein and connecting said front and said rear surfaces (12, 14); iv.) a flattenable bottom surface formed by connecting said front, said rear, and said side surfaces (12, 14, 18), the gussets of the two side surfaces being sealed at the bottom surface with a K-seal; and v.) a top surface formable by connecting said front, said rear, and said side surfaces (12, 14, 18); said bag having a height, a width, and a depth, and an internal volume; vi.) a non-reusable closure; wherein said non-reusable closure has a length that extends along said width of said bag, wherein said non-reusable closure comprises a membrane connectable between said front surface and said rear surface of said bag, said membrane having a user-facing surface, an outer surface, and a tear strength of at least 1 kg/cm 2 (15 pounds per square inch); b.) at least about 6.8 kg (15 pounds) of a particulate, flowable composition contained therein; the bag being characterized in that the membrane is a co-extruded blend of ethylene-derived polymer selected from the group consisting of low density polyethylene, high density polyethylene, ultra-low density polyethylene, and combinations thereof, and in that a plurality of ribs (36a, 36b) is arranged on the outer surface of the membrane, such that a portion of said outer surface of the membrane is sealable to an inner surface of the front surface of the bag and a portion of said outer surface of said membrane is sealable to an inner surface of the rear surface of the bag, with the ribs (36a, 36b) being formed from ultra low/very low density polyethylene.