Joints, Stems, & The Anatomy of Bongs & Dab Rigs

"Water Pipe Joints, Stems, & Anatomy" covers basic information about the many different joint sizes and designs used in the creation of water pipes, dab rigs, and bubblers. You'll also find information about the common overall anatomy of water pipes. This can be a helpful tool when determining which type of water pipe is best suited for you or the size and type of accessories you need for your existing bong, dab rig, or other water filtered smoking pipe. 

Please note that the information contained in this post is not gospel or definitive. All the info here is correct and thorough to the best of our knowledge, however,  If you see something that you believe is incorrect or incomplete please feel free to reach out  and let us know. 

Before we get into joints and stems I'd like to cover the basic anatomy of water pipes. My hope is that learning all the basic parts of a water pipe first will make the information about the intricacies of the pipe easier to understand later. You'll find four images directly below. Each image is a different style of water pipe. It's impossible to cover every nuance you are likely to come across as you venture further into the world of water filtered smoking pipes, but I have done my best to cover all the standard features of most water pipes. Know that we will get more in depth about all the different percolators; the difference between concentrate vs flower rigs; add-ons etc. There is a lot to get into and we hope to cover it all; if not in this knowledgebase then in our more specifically focused blog posts. 

#1- Beaker Base Water Pipe 

Anatomy Beaker Base Water Pipe | Next Bardo Online Head Shop

#2- Straight Tube Water Pipe

Anatomy Straight Tube Water Pipe | Next Bardo Online Head Shop

#3- Bubble Base Water Pipe

Anatomy Bubble Base Water Pipe | Next Bardo Online Head Shop

#4- Hourglass Dab Rig Water Pipe

Anatomy Hourglass Dab Rig w/ Showerhead Perc | Next Bardo Online Head Shop

Anatomy of a Water Pipe:
I'm going to cover a few of the terms in the anatomy images above and then we will move onto a more specific explanation of stems and joints.

Beaker Base: 
Style of base found on many bongs and dab rigs. Shaped much like a beaker you might find in a scientific environment. Designed for easy use and smooth hits featuring a large water reservoir for more filtration and a more stable design that is less likely to tip than others. 

Bent Neck:
The bent neck design offers multiple advantages in function and style. This design in part operates as a splash-guard so no water splashes into your mouth.

Bowl (Dry Herb):
The area of the pipe where you place your dry herb (flower) for combustion. 

Bubble Base:
The second most commonly used base on a water pipe. The advantage of using a bubble base is the amount of water it holds. The more water the more filtration; the more filtration the better the taste and the smoother the hit.  

This is just another term for the "base" really. The area of the water pipe that holds the water and the place the filtration happens. 

The accessory that holds your bowl or quartz banger. Often the downstem is diffused meaning it features slits or holes that act as a percolator helping to increase the filtration. 

Fixed Stem:
Also and often referred to as "stemless" it refers to the fact that the stem is not removable. Instead it is built directly into the water pipe. 

Flared Base:
A flat, circular base that is most often used with straight tube water pipes and sometimes with bubble base water pipes. 

Flared Mouthpiece: 
A flared mouthpiece is just what it sounds like; the glass is flared out where you place your mouth to smoke. It is visually pleasing to some, but more importantly, it creates a stronger seal between your mouth and the water pipe and is more comfortable that a mouthpiece that is flush with itself. 

Honeycomb Disk Perc:
A perc that disk shaped and looks like a honeycomb design. It has a lot more diffusion than a standard perc because it contains many, many holes that amplify diffusion and divide your smoke which translates into smoother more pleasing hits.

Hourglass Chamber:
Mostly aesthetic, however the hourglass base (like a beaker base) holds a large amount of water and created a sturdy relationship between the rig and the surface it sits on.  

Ice Pinch/Ice Catcher: 
Known as both an ice pinch and an ice catch, it allows the smoker to place ice in the tube/neck of the pipe. As smoke travels over or through the ice it is cooled and results in a smother hit for the user. 

The area of the water pipe that holds the removable downstem, or, if the pipe has a fixed stem, the area that holds the bowl or quartz banger. *** Joints are also found on accessories such as a downstem. We will cover that further in the future. 

Maria Ring:
A Maria ring is a cylindrical, protruding glass ring that is usually found on the neck or below the mouthpiece of a water pipe or dab rig. Meant mostly to make pipes look pretty, but can sometimes help with the users grip of the pipe. 

The area of the pipe where you place your mouth to inhale the smoke/vapor. 

Showerhead Perc:
Showerhead percolators have a thin vertical tube that widens into a round chamber. They have slits or holes for increased filtration and diffusion. Their name comes from their resemblance to a showerhead

Most people use the terms bowl and slide interchangeably. I tend to think of "slides" as a one-piece accessory that functions as a bowl and stem together. Usually used in smaller bongs and bubblers that do not have a proper joint, but instead us a rubber grommet to hold the downstem. That said, if you see the term "slide" it is most likely referencing a bowl of any kind. 

This is the area of the water pipe between the chamber and the mouthpiece. I've heard it referred to by multiple names, but tube or neck tend to be the most common. 

Quartz Banger: 
Used exclusively on dab rigs; the banger nail is the part responsible for holding the concentrate when it is heated and where it forms into vapor. The easiest way to think of it is as a bowl for dabbing concentrate. Quartz is an extremely heat resistant glass and is capable of handling the heat associated with dabbing better than common boro glass.. 

Okay!! Now that you are familiar with many of the common features of a water pipe, lets talk about stems and joints!!


10mm Joint: Most commonly found on dab rigs and Nectar collectors, but also used for smaller bongs. The "10mm" represents the size of the joint in which your bowl, slide, or nail will fit into or onto. (10mm = 0.39" = approx. 3/8")

14mm Joint: A very common size joint that is used with both, bongs, and dab rigs. You will also see this joint size used with Nectar Collectors quit often. The "14mm" represents the size of the joint in which your bowl, slide, or nail will fit into or onto. (14mm = 0.551" = approx. 9/16")

18mm Joint: Most commonly used for larger flower rigs, but can also be used for oil rigs and occasionally for nectar collectors. 18mm represents the size of the joint in which your bowl, slide, or nail will fit into or onto. (18mm = 0.708" = approx. 3/4'')

Please note*** You will sometimes see 18mm joints refereed to as 18.8mm or even 19mm. This has to do with where on the joint it is measured. For the purposes of a water pipe you can rest assured that regardless if the joint is listed as 18mm, 18.8mm, or 19mm it is going to fit, so don't sweat it.. 


Example of female joint on water pipeexample image of male joint on bong slide
If you are familiar with the "birds and the bees"; this is a bit like that. A male joint fits INTO a female joint and a female joint fits ONTO a male joint. 
example image of male joint on a water pipeexample image of female joint on a bong slide
So, looking at the pictures above you can see that the male bowl would fit inside the female joint on the water pipe in picture #1 and that the female bowl would fit onto the male joint of the water pipe in picture #2. 

Rule of thumb:
  • If your bong or dab rig has a female joint you'll need male accessories.
  • If your bong or dab rig has a male joint you'll need female accessories.

In the examples above we used rigs with fixed stems to explain gender. When I say "fixed stem", I mean that the stem is built directly into the pipe and cannot be moved or removed. Here are two pictures to illustrate the difference between a water pipe with a fixed stem and a water pipe with a removable downstem. 
example image of a bong with a removeable downstemexample image of a water pipe with a fixed downstem

The joint on a water pipe will always be fixed (built into the pipe), however, that is not always the case with the stem. If you look at the two water pipes in the images above you'll see that the image on the left shows a water pipe with a removable downstem and the image on the right shows a water pipe with a fixed stem. 

What is the purpose of a downstem? All downstems provide suction, pulling smoke or vapor into the water before it gets inhaled. When you force smoke or vapor to travel through the water in this way it cools and filters the smoke which makes for a smoother more pleasant hit. 

Why use a removable downstem? A few commonly noted advantages of a removeable downstem are:
  • The ability to clean your rig much easier.
  • The flexibility around what type of stem you can use.
  • A removeable downstem can be replaced if it is broken. If a fixed stem gets broken it means the death of your pipe.
How do i choose the right size downstem and which one is best for me? 
First, if your water pipe requires a removable downstem then it has a female joint. This is always true which means that you can consider all removeable downstems as "male". Noting that; lets figure out the diameter and the length of the downstem we need. 

Rule of thumb:

18mm female joint = 18mm outside diameter downstem
14mm female joint = 14mm outside diameter downstem
10mm female joint = 10mm outside diameter downstem

As we discussed above, there are three joint sizes. You need to know what the female joint size is on your pipe. It is either 18mm, 14mm, or 10mm. You'll need to measure the inside diameter of the joint on your water pipe. The most common joint size on a bong with a removeable stem is 18mm, so for this example we are going to assume your water pipe has an 18mm female joint. 

Now that we have a joint size; (female 18mm), we know that the downstem we need is going to have an outside diameter of 18mm. Now you have a couple choices. You can find an 18mm/14mm downstem or a 18mm/18mm downstem. The most common downstem is an 18mm/14mm, so we are going to use that size as an example. This means that the downstem has an 18mm outside dimension and a 14mm inside dimension (a 14mm female joint). The male, 18mm downstem fits INTO your water pipes 18mm female joint which now leaves the female joint of the downstem available to hold accessories such as a bowl, slide, quartz banger etc..

The images directly below illustrate what I am saying. The image on the right shows you a 14mm male bowl fitting into the 14mm female joint of the downstem AND the 18mm downstem fitting into the 18mm female joint of the bong. 

image of diameter measurements of an 18mm-14mm downstem...Bong, Downstem, and Bowl measurements example image
How long should the downstem be? 
The easiest thing to do is to measure the downstem you already had in your water pipe, however, if that is not possible then you can use this commonly used pencil trick. Ultimately, you want the downstem to sit approx. 1/2" from the bottom of the chamber of your waterpipe. An easy way to figure out that measurement is to use a pencil or another similar straight object and follow these instructions: 

1. Insert the pencil into the female joint of your water pipe and push it down into the pipe until it sits approx. 1/2" from the bottom of the base of the pipe. 
2. Now, mark the pencil where it sits flush with the joint on the water pipe. 
3. Now, measure the area from the end (where the lead is) to the mark you made on the pencil, and this is the approx. length you'll want to use.  DO NOT GET A DOWNSTEM LONGER THAN THAT LENGTH.

Last but not least, you just need to know how manufactures and retail stores measure the downstem. You do not want to measure the entire downstem from end to end. You want to measure from the tip (the end that sits in the water) to the lowest spot of the joint on the downstem. In most cases the joint is frosted/ground and easy to identify which should make the process pretty straight forward.

The images below show you how downstems are measured and listed for sale. You'll want the measurement you took using the pencil to match the measurement listed by the store you're purchasing from. The image on the left is an 18mm/14mm downstem. The image on the right is a 18mm/18mm downstem. They are both measured in the same way, but look slightly different which is why I am including both images. 

How to measure a downstem instructions...How to measure a bong downstem instructions

Hopefully the pictures above answered any questions about how downstems are measured and what size you need for your rig, but if you still are unsure please feel free to call a customer service rep at 1-800-453-5790 or email us at We are more than happy to help you with any product related questions. 

What is a diffused/diffuser downstem and why do i want to use one?  
A diffuser is essentially a percolator. You'll typically find them on the downstem of a bong, bubbler or dab rig. There are quite a few different varieties of diffuser downstems and while they all perform essentially the same function, you may find you prefer one more than another. One thing in common with them all are slits or holes in the glass of the downstem. The slits work to break up the smoke which produces smaller bubbles and results in a cooling of the smoke or vapor. This process translates into a much smoother and more pleasant hit. 

The most obvious reason to use a diffuser is the smoother hits I mentioned above. Who wants to cough up a lung every time they take a bong hit, right? You'll also notice a second advantage; the ability to taste your smoke. I mean, what's the point of having a thousand different strains of weed if you don't get to taste them?

We will get into more specifics about diffusers and percolators both in this knowledge base and in our future blog posts. Please signup for our mailing list and keep an eye on out for our blog posts if you want to learn more about getting the smoothest, coolest, best tasting hits from your pipe.