Hi mate, with the bottle with something loose in it can you only hear it when it is empty? thanks
Itis basically being sold with a free rattle lol, only kidding...
It will need the reg removing and what ever is loose inside removing, i have no idea what is inside but im guessing perhaps part of the reg..
There is no air in the bottle , so you could be onto a winner if its something simple, or just put another reg on it ...
Thus the cheap price, if i had a spare reg i would do it myself, but frankly i can't be assed..
Hope that helps..