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 has a self-locking snap-in pin to withstand greater loads. The pip prevents the shackle from jamming and keeps the sail slug or slide from abrading the boltrope. The unique snap design is often preferred as an easier to fit alternative with higher strength and reduced elongation under load.
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.