Webbed duct strap processing high tensile and abrasion resistance. This can be used for flex duct as it is easy to cut and staple to joists. The product is chemical resistant and tested to meet UL Standard 2043. Purpose Woven Polypropylene Hanging Strap is designed for the hanging of flexible ducting. Advantages Woven Polypropylene Hanging Strap has high tensile strength of 400 lbs. minimum and 460 lbs. maximum, and is both abrasion and chemical resistant. This strap is easy to cut and is easy to staple to joists.