No link - When the ferrule of the parent body is pushed to the other end, the steel ball automatically rolls out, so the child body is moved out; since the child body and the parent body have no valve, the fluid flows out.
Link - When the daughter body is inserted into the mother body, the ferrule is pushed to the previous position by the force of its spring, so that the steel ball is locked, the fluid flows, and the O-ring is used to prevent liquid leakage
