The hanging chair spring has a length of approximately 10cm (4"), with a steel thickness of 7mm (0.27"). The spring capacity is over 1000lb. The swing springs are super heavy duty, designed to absorb shock and help preserve the longevity of your swing. They reduce noise, vibration, and stress, and will not stretch out. The hammock spring is made of zinc-plated hardened steel with an electric galvanized surface, offering sturdy construction, anti-corrosion properties, and enhanced weather resistance for extended life. The heavy-duty spring is placed between the overhead support and swing chain to provide a more comfortable, softer feel for porch swings, free-standing swings, hammocks, and hammock chairs. The spring hook fits most porch swing bags, hanging chairs, cocoon chairs, hanging egg chairs, wicker basket gardens, hanging hammock chairs, heavy bags, boxing equipment, yard sling swings, and other popular outdoor and sports items.