Stable material: The hanging chair spring is made of steel and galvanized to withstand various types of mechanical damage. Galvanization protects steel from corrosion for years without maintenance. Specifications: Oscillating spring 7mm, 4-speed, total length: 108mm, coiled wire length: 40mm, wire diameter: 7 mm, spring outer diameter: 39mm, spring inner diameter: 27mm, material: galvanized steel, weight: 195g. Spring hook design: Use a special swing spring for the hanging chair. A coil spring wrapped around the center reduces vibrations caused by floating objects. Never worry about waking up even when resting in the hammock. Main features: Hammock springs are particularly suitable for attaching swings, hammocks or garden benches, porch swings, loveseats, hammocks, swings, etc. in the house and garden, balcony or terrace. It is the perfect accessory to mount between the hook and the chain. Service: If you have any questions, please feel free to contact us.