Stable material: The hammock springs are made of galvanized steel, which resists various mechanical damages. The galvanized layer protects the steel from corrosion, requires no maintenance, and has a lifespan of several years. Specifications: Swing spring 7mm, Total length (four positions): 108mm, Winding length: 40mm, Wire diameter: 7mm, Spring outer diameter: 39mm, Spring inner diameter: 27mm, Material: Galvanized steel, Weight: 195g. Spring hook design: The hammock uses a special swing spring. The centrally wound coil spring reduces vibrations caused by floating objects. Even when resting in the hammock, you don't have to worry about being woken up. Key features: Hammock springs are particularly suitable for installing swings, hammocks, garden benches, porch swings, double sofas, etc., on houses, gardens, balconies, or patios. It is the perfect accessory installed between hooks and chains. Service: Please contact us if you have any questions.