It is mainly composed of a D - shaped body and a pin. The body is in a closed D - shape, and the pin is used to pass through the hole on the body to connect other components5. Some pins have threads at one end and are used with nuts, while others are fixed by pins and other methods to ensure the reliability of the connection. It has a variety of specifications, such as M6, M8, M10, etc., and there are also specifications in inches, such as 1/4, 5/16, etc. The rated load range is wide, and the common American - standard shackle specifications on the market are from 0.33T, 0.5T, 0.75T to 120T, 150T, etc., which can meet the needs of different lifting scenarios