A vertical form, fill and seal machine in conjunction with a product supply apparatus provides a continuous, heat sealable plastic film and zipper tape and provides separate, product filled, reclosable, top opening sealed bags. The apparatus includes a means for supplying the continuous plastic film, a means for supplying zipper tape, a means for sealing the zipper tape sections to the film, a vertical fill tube assembly, a feeding means including a film drive roll upstream, film pull belts adjacent the vertical fill tube, a vertical sealing means for sealing the edges of the continuous film to the edges of the continuous zippered cap strip, a horizontal sealing, perforating, and severing means for severing the plastic tube between the first and second horizontal seals, and a tensioning means for horizontally elongating the flexible plastic tube transverse to its length prior to formation of the horizontal seals.