Threaded vs Non-Threaded CO2 Cartridges: How to Tell Which Your Tool Needs
June 14, 2026
The number one reason a CO2 cartridge “doesn’t fit” isn’t the size — it’s the neck. Threaded and non-threaded cartridges look nearly identical in a photo, but they are not interchangeable, and ordering the wrong one is the most common mistake we see. Here’s how to get it right the first time.
The 10-second test
Look at how your tool connects to the cartridge:
- It screws on → you need a threaded cartridge (3/8″-24 UNF threads).
- The cartridge drops into a sleeve and gets pierced when you tighten a cap or lever → you need a non-threaded cartridge.
If you still have an old cartridge that worked, check its neck:
- Threaded: visible screw threads below the tip. The tool seals against a gasket as you thread it in.
- Non-threaded: a smooth, rounded neck with no threads. A sharp pin punctures the seal.
Why they’re not interchangeable
A threaded tool relies on the cartridge’s threads to pull it tight against a sealing gasket. Drop a non-threaded cartridge in and there’s nothing to grip — it won’t seal and gas escapes. Force the wrong neck into a head and you’ll waste the charge, damage the seal, and risk a sudden release of pressurized gas. Match the neck to the tool, every time.
Which tools use which
| Tool | Neck | Typical size |
|---|---|---|
| HVAC drain gun | Threaded | 16g (45g for long runs) |
| Modern bike inflator | Threaded (most) | 16–25g |
| Older / budget bike inflator | Non-threaded | 12–16g |
| Life-jacket re-arm kit | Threaded | 16–33g (check the kit) |
| Airsoft / BB gun | Non-threaded | 12g |
| Soda siphon | Non-threaded | 8g |
When in doubt, the CO2 Finder walks you to the exact cartridge by tool and size.
”Both” exists — the 16g
The 16g is the one size sold in both threaded and non-threaded versions, because it’s used across so many tools — drain guns, bike tires, re-arm kits. That’s exactly why it’s the size people order wrong most often. Confirm the neck before you buy 16g. You can see the full range on the CO2 Cartridges page, and there’s a deeper breakdown in CO2 cartridge sizes explained.
FAQ
Can I use an adapter? Adapters exist for some bike applications, but they add a failure point and another seal to leak. For drain guns and re-arm kits, don’t adapt — buy the right neck.
Are threaded cartridges higher quality? No — the neck is just a fitting choice. Both are the same leak-tested, food-grade CO2.
My tool didn’t come with cartridges. How do I know which it takes? Check the manual, or email us a photo of the head and we’ll identify it.
Buying for a shop or fleet? Request bulk pricing — most threaded and non-threaded sizes ship the same or next business day from Minnesota.