Southwire cable tie/duct straps are the superior tie to use for HVAC installations. UL 181 B-C approved for use on flex duct. These cable ties are proudly MADE from a UV-resistant industrial strength Nylon 6/6. Perfect for supporting air ducts and other miscellaneous items that need to be tied together. 50-Pack, 24 in. black cable ties with 175 lbs. tensile strength for extra-durability. Working temperature range: minus 40?C to 85?C or minus 40?F to 185?F. Rated for indoor and outdoor use. cULus listed. This product ships in approximately 1 days