Extension Ball Bearing

Extension Ball Bearing
hookah pipe part- unknown purpose?

i have an inexpensive hookah, and at the base of the stem, above the bowl there are two extensions, one is for the hose connector, and the other is capped off. This capped extension has a ball bearing in it that served a purpose (i think). what is the purpose for this part? thank you.

it's the purge valve, if it looks like on this http://www.hookah-shisha.com/p-5484-mya-saray-hookah-petite-1-hose-hookah.html
then yes it's a purge valve all it does it allows you to blow into your hookah and get rid of any smoke that seems harsh or you just don't want any smoke in your base if you have any pic's of post it up so i can and others make sure what we are saying is right hope this helped you out