Material: Made of high quality steel. Heavy duty steel construction. Good performance. Higher corrosion resistance, not easy to rust, more durable. Good performance. Can be used with confidence. Size: Wire Diameter: 7mm/0.28″, Length: 106mm/4.17″. Sturdy, solid, can hold up to 200kg (440lbs) for 1 piece of spring and 400kg (880lbs) for 1 pair of springs. Function: The spring helps relieve shock stress, offers a cozier, softer feel and will increase the life of your hammock, in addition to your mounting surface. Simple Assembly: With hooks at both ends, the porch swing spring easily connects to your hammock chair without using any tools or complicated operation. Versatile: Suitable for almost any garden patio porch and garden swing, hammock, hanging chair, punching bag, cocoon, chair wicker basket rattan, etc. Due to manual measurement, there will be some errors.