This is a plastic shackle used to secure a slug or slide to a sail. It is injection molded from a tough nylon to absorb sudden impact loads and features the strongest screw design closure that permits easy detachment and re-attachment (screw is included).
Sail shackles are popular due to their quick installation time. This shackle must be used with a pressed #1 or #2 spur grommet in the edge of the sail. Plastic or nylon shackles do not need a plastic insert to protect the sail.