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Downstem Size Guide

Downstem Size Guide - Tips on How to Measure The Downstem of a Bong

What is a Downstem?

A downstem is the long tubular piece of glass that connects your bong bowl piece to the main water chamber of your glass bong. Creating an airtight seal between the glass pieces, it facilitates suction pressure that’s required to pull the smoke from your bowl piece down into the water chamber as you inhale. Without it, your smoke would simply climb through your piece without first passing through the water.

These glass pieces can be removable or fixed to the piece. Fixed downstems are built right into your piece and connect to your percolator. While it’s one less piece to worry about, if broken, you can’t easily replace them like you can with detached downstems.

Measuring for a Downstem

When buying a new downstem, you’ll need to know two things: joint size and length. These are the two standard measurements that headshops use when selling. Downstem sizes come the same way joint sizes do, in the standard sizes of 14mm, 18mm, and the less common 10mm for mini dab rigs. If you need to figure out your joint size, check out our easy guide here. All you’ll need is a penny and you can find your joint size in seconds.

To determine the length you’ll need, we recommend using the pencil method. Simply grab a pencil or pen, your bong, and a ruler of some sort and you’re ready. The length of the downstem is measured from the bottom of the frosted joint to the bottom of the stem like photographed below. Usually the bong’s joint will also be frosted to help you more easily determine where to start measuring.


How to measure the length of your downstem

 Once the pencil is down far enough into the water chamber, remove it carefully and measure the length you’ll need with a ruler.

Types of Downstems

There are several types of downstem beyond your basic natural downstem. The same way that bongs have percs, some downstems, referred to as diffused downstems, have the ability to help break up your smoke. Some may have tiny slits the way that a tree perc does whole others have holes like a honeycomb perc. While they all serve the same purpose, to help your smoke travel 

Downstems can also work as adapters! You most often see this in 18mm pipes that come with a 14mm/18mm Low Profile Downstem, meaning that it fits into an 18mm joint, but uses a 14mm bowl piece or slide. 14mm is the most common size of bowl piece, so unless you have a specific 18mm slide that you’re really attached to, we recommend getting the LoPro downstem.

14mm vs 18mm Downstem Size


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