I broke my original roor downstem and bowl. I'm looking to upgrade to a RooR diffuser downstem and don't which size to order. Here is a pic of my downstem measured in at 6.5 inches which converts to 16.8cm and looks really close to bottoming out at 16.8mm. I have two choices for replacement downstem in 15.5cm that will work but will requires more water in the bong to work or 17cm and risk the downstem not fitting right as it "looks" like it is going to bottom out with the original roor downstem measured at 16.8mm.
