A Spunbond polypropylene or polyethylene outer sleeve extension, ultrasonically sealed for hermetic closure. Perfect for fantastic powders requiring utmost sift resistance. Breathability: The woven structure permits enough air circulation, valuable for items that need air flow. One of the standout options of Bopp laminated pinch bottom bags is their form. https://www.jtfpack.com/products/bopp-pinch-bottom-bags/