This Sentry II bag features a double layer of fabric for extra strength and has efficient drainage. Fabric is made of spunbonded polypropylene fibers, and a single layer weighs 2.24 oz/sq yd, and has a tensile strength of 26 lbs/inch, yet has an air permeability factor of 300 cu ft/sq ft. Each sample bag comes with a 2 x 3" sewn-in tag for sample identification and tie tape sewn into seam. Shipping weight for 25 bags is 8 lbs.