With water pipe smokers in particular, the different bong features may cause some confusion and often results in a mispurchase. That’s why we want to give you some information on the different glass joints.

A Bong’s Joints

A Joint is the connection part of Glass bongs, usually the lower part of the downpipe that goes into the water and and the connection of bowl to the stem or diffuser. They always need to have the same joint size with the most common being 14.5mm and 18.8mm.
Unfortunately, these joints are rather fragile and prone to break. In the worst case scenario, the broken joints may make the bong unusable. Therefore, some manufacturers came up with some ideas.

Hammer Joints

The Hammer Joint prevents the problem with the rather thin glass connection parts which may crack due to careless movements and ruin the downstem—or even worse, the whole bong itself. The Hammer Joint has a thicker glass around the upper connection and thus tolerates even a rougher treatment. Nevertheless, it has its limits. No glass bong is absolutely break-proof.

Solid Tank Joint

The Tank Joint goes one (small) step further. In comparison with the Hammer Joint here the glass connection is just a hint thicker. Well known for their Tank Joints are the G-Spot Bongs among others.

Inside Cut

The Inside Cut works in a similar fashion using the glass material of the pipe itself. The glass on glass connector for the downpipe or diffuser is here the opening on the bong itself and does not stick out. Thus, the bong body is less susceptible to lateral tensile breaking loads and the associated damage. If there occurs a crack, it will be only the downpipe.

Joint Sizes

Regarding the joint sizes, different standards are established by now. Usually, you get the bongs or waterpipes and the necessary accessories with the following diameters:

  • 12.5mm
  • 14.5mm
  • 18.8mm
  • 29.2mm

The most common sizes are the two medium ones. Sometimes you may encounter 12.5mm with very small glass water pipes, and 29.2mm is restricted to the extra large monster bongs.


If you e.g. want to use some old bong accessories—like bowl, downpipe or diffuser—with a new purchase but the joint sizes don’t match, you may find an adapter very helpful. They are easily available for the most common sizes, reducing from 18.8mm to 14.5mm or the other way around. Other adapters for the small joint sizes to the larger sizes are very rare and hard to find.