The DiversiTech® 710-103 silver, 3 in. x 100 yd. webbed duct strap has a high tensile and abrasion resistance. It can be used for flex duct since it's easy to cut and staple to joists. It's chemical resistant and tested to meet UL Standard 2043. Diversitech Hanging Duct Strap, 400 to 460 lb Capacity, 100 yd Length, 3 in Width, For Use With: Flexible Ducting, Polypropylene Woven, Silver, Import