So I just bought a very nice bong off grasscity from graceglass and i'm very happy with it. I'm now interested in upgrading it a little bit by adding a precooler attachment to the joint. Only problem is I don't know what will fit my bongs joint size being 29.2mm>18.8mm. I found a precooler that is 18.8mm joint size, will that fit it or are there specific joint sizes that only fit this measurement 29.2mm>18.8mm? or is 29.2mm>18.8mm the same thing as just 18.8mm, i'm very confused. Any help appreciated. Screenshot of bong is posted