Sturdy MaterialThe hanging chair spring is made of steel and galvanized to resist various types of mechanical damage. Galvanizing protects steel from corrosion for years without maintenance. SpecificationsOscillating spring 7mm 4-speed-total length: 108mm coiled wire length: 40mm wire diameter: 7mm spring outer diameter: 39mm spring inner diameter: 27mm material: galvanized steel weight: 195g Spring Hook DesignUse a special swing spring for the hanging chair. A spring coil wrapped around the center reduces vibrations caused by floating objects. Never worry about waking up even while resting in the hammock. Main FunctionsHammock springs are especially 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 accessory to mount between the hook and the chain ServiceIf you have any questions, please feel free to contact us.