Looking for heavy - duty zip ties These 20 in. black zip ties are a great choice. Made of Nylon 66 (PA 66), they are extra large with a 12mm width, offering high durability. They can withstand temperatures from - 31°F to plus 185°F, are fire - resistant (rating 94V - 2), and waterproof. With a 250 lbs. tensile strength, they're suitable for tough jobs. They're multipurpose, perfect for cable organization, hanging heavy items around your home, pergola, or workshop. The self - locking design with 4 - teeth ratcheting is easy to use, and you can reuse them with a pin. The 40 - pack gives you enough for multiple projects, bringing convenience to your daily life and DIY tasks.