So i see some of the part that have a hole like this. I wonder what is their purpose ? Is it have something to do with the air ? like let the air escape outside when you put the ball joint on. This is not always the case in every toy, some have this, some don't. There are also a toy i have and they have some tiny hole in the ball joint it self and not the part you put the ball joint in. Could it be with air it effect the friction ? or companies just simple want to save some gram of plastic ?