Heavy-duty steel construction. Zinc plated and clear coated for increased weather resistance. Very strong and can be used for a long time. The spring helps relieve stress from impacts, provides a more comfortable and softer feel, and will increase the lifespan of your hammock, as well as your mounting surface. Compatible with almost all punching bags, boxing bags, hanging chairs, cocoons, egg chairs, wicker chairs, etc. Spring capacity rating of over 700 lbs. Package Contents: 2 x Carabiner. Wire Diameter: 7mm/0.3" (Approx.), Length: 108mm/4.25" (Approx.).