Water pipes & bongs
by Hemper
The Anystem Adjustable Downstem is a silicone-and-glass replacement downstem that telescopes from 3.8 to 6 inches, fitting practically any water pipe you own. Made by Hemper, it pairs a borosilicate glass percolator with a flexible silicone body — so you get proper diffusion without the constant fear of snapping your downstem while cleaning or travelling. One piece, two joint sizes (14mm and 18mm), and enough adjustability to dial in the water level on just about any bong in your collection.
The Anystem fits both 14mm and 18mm ground glass joints — the two most common sizes on standard water pipes. Not sure which you've got? Measure the inner diameter of your joint opening. 14mm joints are roughly the width of a pencil; 18mm joints are closer to a 1-cent coin. If you're still unsure, the silicone sleeve on this downstem grips both sizes snugly, so you're covered either way.
| Specification | Detail |
|---|---|
| Brand | Hemper |
| SKU | HS2453 |
| Adjustable length | 3.8–6 inches (approx. 9.7–15.2 cm) |
| Joint compatibility | 14mm and 18mm |
| Percolator | Built-in borosilicate glass percolator |
| Body material | Heat-resistant silicone |
| Percolator material | Borosilicate glass |
| Use case | Replacement downstem / travel spare |
Complete your setup with a fresh bowl piece — a 14mm or 18mm glass bowl from our water pipe accessories range pairs directly with the Anystem. If your bong is looking tired overall, browse our full water pipes and bongs selection for an upgrade that matches your new downstem.
We've lost count of how many customers have walked into a shop holding two pieces of what used to be a perfectly good glass downstem. It's the single most breakable part of any water pipe — thin, rigid, and constantly being pulled in and out for cleaning. One slip on a tile floor, one slightly too-vigorous scrub with a pipe cleaner, and you're shopping for a replacement.
The Hemper Anystem solves this in two ways. First, the silicone body absorbs the kind of knocks and drops that would shatter a standard glass stem. You can genuinely bend this thing without damaging it — it feels rubbery and substantial in the hand, not flimsy. Second, the telescoping design means you're not stuck hunting for a downstem that's exactly 4.5 inches or exactly 5.25 inches. Slide it out to 6 inches for a tall beaker, push it down to 3.8 for a compact piece. That 2.2-inch range of adjustment covers the vast majority of bongs on the market.
The one thing to watch: the glass percolator section at the bottom is still glass. Borosilicate, so it handles heat brilliantly and is tougher than regular soda-lime glass, but it's not indestructible. Treat that end with a bit of care and you'll be fine. Compared to something like the Invincipole Infinity Shatterproof Downstem (which goes fully shatterproof at a higher price), the Anystem strikes a good balance between diffusion quality and durability for the money.
Here's where this thing really earns its keep. If you've ever tried to transport a glass downstem to a mate's house wrapped in a sock inside a backpack, you know the anxiety. The Anystem's silicone body means you can toss it in a bag without padding. We've seen customers keep one as a permanent travel spare — their good glass downstem stays safe at home, and the Anystem goes everywhere else. At this price point, it's cheap insurance against ruining a session because someone knocked the table.
The diffusion from the borosilicate glass percolator is genuinely decent, too. It's not going to match a multi-slit scientific downstem from a high-end brand, but for a universal-fit adjustable piece, the bubble break is smooth and even. You'll notice a clear difference compared to a basic open-ended downstem. The 6-inch maximum length means it works in beakers up to about 35 cm tall — beyond that, you might find it doesn't reach the water.
If your water pipe has a standard 14mm or 18mm ground glass joint and needs a downstem between 3.8 and 6 inches long, yes. That covers the vast majority of bongs on the market. Measure your current downstem length and joint diameter to be sure.
Yes. The Anystem's silicone sleeve adapts to both joint sizes, and the bowl seat accepts both 14mm and 18mm bowls. You can mix and match depending on what you've got.
The silicone body is heat-resistant and sits away from the direct flame — your bowl piece takes the heat, not the downstem. The borosilicate glass percolator at the bottom handles high temperatures without issue. Normal use won't cause any problems.
Pull it out, soak the glass percolator section in isopropyl alcohol for 15–30 minutes, then rinse. Wipe the silicone body with warm water and dish soap. Don't soak the silicone in alcohol for hours — it stays in better shape with a quick wipe-down.
The silicone body won't — that's the whole point. The borosilicate glass percolator at the tip is tougher than standard glass but can still crack on a hard surface. In practice, the silicone absorbs most impacts. It's far more durable than a fully glass downstem.
Three things: the silicone body makes it nearly unbreakable during handling, the adjustable length fits multiple bongs instead of just one, and it accepts both 14mm and 18mm joints. A glass downstem gives you slightly better flavour purity, but zero flexibility and zero drop resistance.
You can, but it's easier to set the length before inserting it. Pull the downstem out, telescope it to the length you need, then slide it back in and check the water level. Fine-tuning in place works, just be gentle.
Last updated: April 2026
