These commercial grade Growers Edge? HVAC Zip Ties are very simple to use and feature a locking mechanism that gives ducting a firm hold. Made from thick, heavy duty natural colored nylon. The 36 in tie can fit up to 10 in ducting and the 48 in tie can fit up to 14 in ducting. These zip ties will work great for all your fastening needs. Attach flexible ducting to reflectors, fans, carbon filters and more. Use to safely secure products to your wall or ceiling. They also work great to hold pre-filters tightly on your carbon filter.