The Hammock Chairs Swing Spring Sets are made of 304 stainless steel. The surface has a waterproof and transparent coating, providing high hardness, strength, durability, and a longer lifespan. Holding a weight of 1300 lbs: Each heavy-duty stainless steel spring can support a weight of up to 1300 lbs. Safety Design: The swing spring features plastic caps covering the ends of the wire to prevent scratches and snagging on fingers or hanging ropes, and to prevent the springs from detaching from the hooks. The premium heavy-duty wire ensures it will not break under heavy loads. Anti-Rust: These heavy-duty porch swing springs are made of stainless steel and chrome-plated, making them easy to clean and resistant to rust, whether used indoors or outdoors. Widely Used: These porch swing spring kits are tightly coiled for shock absorption. They can be used for swing benches, hanging chairs, hammocks, hammock chairs, and punching bags, as well as for industrial applications where vibration reduction and shock absorption are needed.