Then I’ll open up that seam and stitch it again making sure it never pulls out I’ll mark it in quarter sections. And then I leave a half inch opening at the center front seam.pout tops (or top spouts) are one of the most common bulk bag top styles. A spout top is a standard bulk bag feature that includes a narrow cylindrical tube sewn onto a flat base. The flat base is sewn into the body of the FIBC to form a fully closable top panel.Excellent for drawstring pants, warm-up pants, and pajamas.Duffle top bulk bags have a thin lightweight top panel that is the same width and depth as the four sides of the bag. The larger opening provides more flexibility in filling options and the types of machinery it can be used with.