K20 Tools - Fast Cap Adapter Compatible with BYRNA SD EP LE - Boost Cartridge Quick Change with Hex (Black)

I bought the Fast Cap Adapter for my Byrna SDXL launcher and I am very happy with it. It makes changing the CO2 cartridge so much easier and faster than using the factory cap and the magazine tool. I can just twist the cap by hand and replace the cartridge in seconds. No more fumbling with the tool or worrying about losing it. The Fast Cap Adapter is also compatible with the Byrna Boost Adaptor (XL), which allows me to use 12 gram CO2 cartridges instead of 8 gram ones. This gives me more shots per cartridge and more convenience, as 12 gram CO2 cartridges are widely available everywhere. The Fast Cap Adapter is made of stainless steel and has a polished finish. It looks great and feels sturdy. It fits snugly on the CO2 chamber and does not leak or rattle. It is easy to install and remove, and does not damage the launcher or the cartridge. I highly recommend the Fast Cap Adapter to anyone who owns a Byrna SD, EP or HD launcher. It is a great accessory that improves the performance and usability of the launcher. It is worth every penny and I am very satisfied with it.

Works great, fast and easy to unscrew and replace CO2 cartridge. My Kydex IWB holster needed a slight mod for the extended length but that was fairly easy.

11/26/2025 - I see differing reports on how these look in the reviews so I'll confirm that as of this date they are the matte black finish, brand text on the side edge (not front as pictured), and threaded correctly for proper fit. Looks and fits perfect in my opinion and the build quality is good. Easy to screw on an replace and the price is right. I think the grip texture on these is better than what I'm seeing from some of the other options too.

These work on an SD

Great piece quick shipping

Works great, but I am a little disappointed that K20 decided to put the K20 Tools on the side of the cap, and not on the front - I actually liked that.

That's all this is and all it needs to be. The Byrna will let you empty a few mags on one CO2 cylinder, so maybe it's not important to be able to quick-change the cylinder like it could be to load a new mag. Still, having to find an Allen wrench when you do need to put in a new cylinder is a pain. Put this in its place and screw and unscrew using your fingers. The Byrna really ought to come with this piece.

Fits. Works. Improves. What more do you want? Even if you tighten it a bit more with the mag tool and have to loosen it with the mag tool (which you don’t have to do at all, but you can if you want), it’s still a massive upgrade from the original design.

Easier than using the mag key . Thank you !

Très pratique

Unfortunately the wrong finish was sent to me. The listing has the finish as matte black, however the item sent was unfinished aluminum. Disappointing, as this does not match the rest of the Byrna. That said, it does fit.