MATERIAL: It is made of high quality rubber. The hook is made of high quality plastic. It is sturdy, weatherproof, durable and corrosion resistant. Extender with hook function: Multifunctional rubber tensioners keep the tent stable. 25 cm elastic band with hook extensions to 50 cm. And the tarp tensioner features a plastic hook that keeps it securely in place. Used rubber tensioner with hook: Our extensions with hooks are suitable for tarpaulins, camping, boat shoes, tents, gardens, ramps, caravans, etc. commercial applications. Bungy rope with hook holder: The bungee rope is easy to thread through the animals and holder and then snaps onto the hooks. You can also wrap a few small rubber bands around it to increase the length. Note: The data is all measured manually, please allow 1-3cm error due to the difference in light and display, there may be color difference, please refer to the actual item received.