Our steel swing chain has a smooth zinc finish is 4/O Aught and Grade 30. The links are 1” long and the opening is ½” wide. Any of our S-hooks or Shackles can be used with this chain. Chain that is not bought from a playground manufacturer does not have the quality control and have been known to have weak links and can contain air bubbles. This product should last 2 years in harsh conditions and up to 5 years in optimal conditions. Some conditions may require replacement sooner. Tensile strength 3900 lbs. Sold per foot.