A retaining ring, also known as a sleeve, retaining ring, shaft collar, positioning block, etc., is a ring-shaped part with fixing and positioning functions. It can be classified according to different materials, structures and usage scenarios, such as metal retaining rings (steel, stainless steel, etc.) and plastic retaining rings. In addition, according to different connection methods, it can also be divided into various types such as stop screw type, open type, separation type, handle type, etc.