A Spunbond polypropylene or polyethylene outer sleeve extension, ultrasonically sealed for hermetic closure. Perfect for fine powders necessitating maximum sift resistance. Polypropylene Multifilament Yarn is produced by extruding polymer through spinnerets and combining the extruded filaments alongside one another right before winding to really make it a yarn. 100% Reusable https://www.jtfpack.com/products/bopp-pinch-bottom-bags/