The two pull pins of the head of the lock head are used to slide the slider, the two raised portions are used for axial positioning, and the middle three holes are used for mounting the pin spring and the large tube pin. The large tube pin can be pressed to stop the movement of the handball, which is the key to the handling of the handball. Two wide slots at the end of the large tube are used to mount the lock. When the large tube is rounded, there is a wide gap at the interface. The function is to cooperate with the convex ribs in the handball to prevent the radial rotation of the handball on the large tube. It can also cooperate with the hook to prevent the external handball and the large tube. Rotate around the threaded flange.