I'm still trying to get my bearings with bong sizes and such. I'm considering buying this bong... The description says it comes with a joint size of 14.5mm, and a non-diffused downstem that is 10cm long. I want to purchase a new downstem and saw that EHLE also had a diffused downstem, but I'm not sure what size to purchase because the closest size to the original downstem is 10.5...help please? Thanks in advance