The chain spring buffers the force of a storm and provides better protection for your home door. Material: Made of alloy steel, surface plating process. Easy to install: All you need to do is measure the length of the fixed point first, drill holes, and link the three-point fixing screws finally. Protection: Prevent damage caused by the storm to doors and walls, and minimize door swing or collision. Application: Suitable for various types of doors, including exterior swing doors, wooden or aluminum doors, composite doors, outdoor doors, and sheds.