These Halyard Shackles are the long variety where the length is longer than the short type halyard shackles that we also sell. Other than that they are designed to achieve the same purpose. They have a key Pin and a secondary pin to keep the lanyard secured to the halyard. The secondary pin is removable, and is held in place by a mini split ring. The main pin is of the key pin variety, where it requires rotating only half a turn to release. They are sometimes refered to as Double bar long dee shackles, due to the two bars incorporated in its design. Perfect for marine use due to its Marine grade stainless material.