The anchor chain is generally provided with a swivel group at the end connected to the anchor. The main function of the swivel ring is to prevent excessive twisting of the anchor chain during the mooring process. The ring bolt of the swivel ring should face the middle link for the purpose of Reduce friction, the ring bolt and its body are on the same center line, and can rotate freely. In practical applications, A-type swivel shackle and B-type swivel shackle are often used. The A-type swivel shackle is directly connected to the anchor, and the B-type swivel shackle is directly connected to the end of the anchor chain, enhancing practicability.