The swivel-shackle (often called super-swivel) was made to minimize the space between the anchor and the chain. It can connect both to a crown-shackle and also direct in the anchor-shank. The other end fit a studless endlink or a common link with stud. These shackles are a more expensive solution then the traditional swivel-forerunner, but often used to avoid the swivel in the chain-stopper.