Short answer: bong parts fit by two things, joint size and joint gender. Almost every water pipe uses one of three sizes: 10mm, 14mm, or 18mm (also sold as 19mm). A male piece slides into a female joint of the same size. Find those two facts on your pipe and you can replace a bowl, downstem or adapter without guessing.
- Lost or broken bowl: match the joint the bowl sits in. For a 14mm female joint, the GRAV 14mm Cup Bowl is a small bowl and the GRAV 14mm Male Octobowl holds more and has a glass screen built in.
- Broken downstem: match the top joint, the bowl receiver and the length. The GRAV 4.5-inch and 3.3-inch Fission downstems fit 19mm downstem joints and take 14mm bowls.
- Tired of breaking bowls: the Smoke Honest Stainless Steel Bowl Piece fits standard 14mm joints.
The three joint sizes
Glass joints are tapered and frosted so they seal without a gasket. The size name comes from the joint's width:
| Size | Width at the wide end | Where you'll see it | Bowls we stock |
|---|---|---|---|
| 10mm | about 10 mm | Mini water pipes and small bubblers | GRAV 10mm Cup Bowl |
| 14mm | about 14.5 mm | Most standard water pipes and bubblers; the usual downstem receiver | GRAV Cup, Caldera, Triple Pinch and Octobowl; MJ Arsenal Summit; Smoke Honest steel bowl |
| 18mm / 19mm | about 18.8 mm | Larger water pipes, downstem joints, the GRAV Large Gravitron | GRAV 19mm Octobowl, GRAV 19mm Funnel Bowl |
18mm and 19mm are the same joint: some brands round 18.8 mm down and others, including GRAV, round it up. My Bud Vase pieces are the exception. They use the brand's own 9mm bubble bowls, so replace those from the same line, for example the My Bud Vase Amber Bubble Bowl.
Male vs. female joints
A male joint is frosted on the outside and slides in. A female joint is frosted on the inside and receives it. Most water pipes have female joints, so they take male bowls. The part you buy must be the opposite gender of the joint it goes into, in the same size.
Quick check: if the frosted section of your old bowl is on the outside of its stem, the bowl is male and you need another male bowl of the same size.
How to measure a joint
- Clean and dry the joint so you can see where the frosted section starts and ends.
- For a female joint, measure across the inside of the opening. For a male joint, measure across the outside at its widest point.
- Compare with the table: about 10 mm is 10mm, about 14 to 15 mm is 14mm, and about 18 to 19 mm is 18mm/19mm.
A ruler with millimeter marks works, and calipers are easier. If a bowl you already own fits, its product page or box usually states the size.
Downstems: three things to match
A downstem carries smoke from the bowl down into the water. To replace one, match:
- Top joint: the end that slides into the pipe's downstem joint, often 18mm/19mm.
- Receiver: the female joint the bowl sits in, often 14mm. A 19mm-to-14mm downstem has a 19mm top and a 14mm receiver.
- Length: listed downstem lengths normally leave out the frosted joint at the top, so measure your current one from the bottom of that joint to the tip. Too short and it may not reach the water; too long and it can hit the base.
Downstems we stock
- GRAV 4.5in 14mm Fission Downstem: 19mm top joint, 14mm receiver, 4.5 inches long.
- GRAV 3.3in 14mm Fission Downstem: the same joints at 3.3 inches, for smaller beakers and straight tubes.
- GRAV 14mm Adjustable Downstem: extends from 4 to 6 inches and diffuses through a tri-cut showerhead. GRAV lists it for beaker and straight-tube pipes with angled 14mm joints.
- Chill Unbreakable Aluminum Downstem: aircraft-grade aluminum, threaded to adjust from 3 to 5 inches, and takes 14mm bowls.
Some downstems are fused into the pipe and cannot be removed. If yours does not come out, you only need a bowl that fits its receiver.
Bowls: size, capacity and screens
- GRAV 14mm Cup Bowl: about 0.25 g, with a glass grip ring; good for smaller pipes and bubblers.
- GRAV 14mm Caldera Bowl: holds up to 0.5 g, in clear and colors.
- GRAV 14mm Triple Pinch Bowl: three glass pinches hold material in place and catch ash; a smaller bowl.
- GRAV 14mm Male Octobowl: about 0.5 g with a glass screen built in, so there is no separate screen to replace.
- MJ Arsenal Summit 14mm Bowl: a 14mm male bowl that fits most 14mm female joints.
- Smoke Honest Stainless Steel Bowl Piece: a 14mm metal bowl for travel, or anywhere glass tends to break.
- GRAV 19mm Male Octobowl: about 1 g with a built-in glass screen; fits 19mm female joints, including the neck of the GRAV Large Gravitron.
- GRAV 19mm Funnel Bowl: a funnel-shaped bowl for 19mm female joints.
- GRAV 10mm Cup Bowl: a small bowl for 10mm female joints on mini pipes.
Adapters and drop downs
An adapter changes a joint's size or gender. A drop down moves the joint lower and further from the body of the pipe. The GRAV 14mm Female to 14mm Male Drop Down slides into a 14mm female joint and gives you a new 14mm female joint further from the glass, which keeps heat away from the main piece.
Size-changing adapters, for example 18mm to 14mm, let one pipe take a different size of bowl. Check the size and gender of both ends before you buy.
Parts for specific pieces
- GRAV Large Gravitron: the replacement bottle with silicone grommet.
- Stündenglass: a replacement glass globe, the hose assembly and the V2 maintenance and seal kit.
- Puffco Peak Pro: the Peak Pro Glass and the Joystick Cap.
Browse everything in our replacement parts collection.
Keep joints clean so parts keep sealing
Residue in a joint stops parts from seating and can make them stick. Close the pipe's 14mm joint with a GRAV 14mm Glass Cleaning Plug while you shake cleaning solution through it. Soak bowls and downstems in isopropyl alcohol, then rinse with warm water. Our glass care guide covers the full routine.
Bong Parts FAQ
Are 18mm and 19mm bowls the same?
Yes. Both names describe the same joint, about 18.8 mm wide, and the parts are interchangeable.
Will a 14mm bowl fit an 18mm joint?
No. It will sit loose and leak air. Use an 18mm-to-14mm adapter, or a downstem with a 14mm receiver.
Do I need a screen?
Not with a bowl that has a screen built in, such as the GRAV Octobowl or Triple Pinch. With a plain cup bowl, a slightly coarser grind keeps material out of the stem.
Why is my bowl stuck?
Residue has built up in the frosted joint. Soak the joint area in isopropyl alcohol, then twist gently rather than pulling straight out.
