Frequently Asked Questions    How To Install    Choosing Your Tubing    Measuring Your Filament

How to Choose Your Fittings

Fittings tend to wear out and loose teeth, so its never a bad idea to swap in new ones when you change your Bowden tube.

What are the differences between them?

First, the size of the tubing it accepts. Bowden tubes for 1.75mm filament are 4mm outer diameter. Part numbers beginning with PC4 indicate "Push Connector 4mm"

The next difference is threading. Most Bowden systems use either an M6 ("Metric 6mm"), M5, or M10 thread. 01 Threading is also common, which is a 1/8 inch NPT thread. The distance between the threads is called the pitch.

Which fitting is right for me?

The easiest way it to look closely at the pictures, paying close attention to the measurements. We are working to build a list of printers for each fitting size, but it isn't complete yet. Please help us out by emailing or tweeting at us, and let us know what printer you're running, and what fittings it uses.

Don't see your printer listed here? Help us build our database by emailing or tweeting @CapTubes with pictures and measurements of your fittings.

Fitting (Size-Thread)


This is our most popular fitting, used by the Creality CR-10*, and many of the newer RepRap printers. We also carry a PC4-M6C, which is a more compact, lightweight version.

*Note: There has been some confusions surrounding this. All CR-10s use a PC4-M6 fitting at the extruder end, but Creality appears to utilize a few different fittings at the hot end, including PC4-01 and PC4-M10. Their fitting is different than ours however. See below.


This is the Compact version of the PC4-M6


This is another common size for RepRaps, and is utilized in the Monstah Adaptor for the popular HE280 hotend.


This is used in some of E3D's hot ends, as well as most TEVO printers. There are TWO versions of the M10 fitting. Be sure to check the pitch of the threads for the best fit. We have M10*0.9mm fittings and M10*1.0mm fittings. More pictures coming soon.

Our Creality CR-10 uses a PC4-M10*0.9mm fitting at the hot end. Note that we have not been able verify that they all use the same one.

As of June 2018, the M10 fittings we have in stock do NOT allow the tube to pass all the way through, like the CR-10. We are working on getting some of those. They can be modified to do so however. All you have to do is carefully drill out the end with a 9/64 bit. Be careful not to drill to far and damage the teeth.

They can also be used as-is by cutting an additional piece of PTFE to go on the other side of the fitting, down into the hot-end for a 'quick disconnect' style set-up similar to the Monstah adapter.


This fitting has an 1/8 inch NPT thread. This is similar to an M10 except with a slight taper. Note that similarly to our M10 fittings, these do not allow the tube to pass all the way through, but can be modified to do so (see above. )


This is an M10 threaded fitting for our 6.2mm tubing, for 2.85mm filaments. Note that these do not allow the tubing to pass all the way through, but can be modified to do so with the help of a 5/64 drill bit (see PC4-M10 above for more details.)

Monstah Adapter

Direct from Mastermind Sarah from New Zealand; we introduce you to the Official Monstah Adapter. Working with Sarah, Capricorn is your Premiere North American distributor. Only seems “fitting” we pair the adapter with our premium XS tubing to provide the best defense against the infamous HE280 puck!

What is the HE280 puck? If you’re unfamiliar with the HE280, it’s a hotend offered by another wonderful Hoosier company, SeeMeCNC; unfortunately, it can be a challenge to get the PTFE tube seated properly against the heat break to prevent pooling of plastic from forming, aka the dreaded puck! The puck leads to feeding inconsistencies, jamming, and loads of colorful words shouted over another failed print. Time to “Scare the Puck Out!” and outfit your HE280 with an Official, Capricorn XS enhanced, Monstah Adapter!

What if I accidently purchase the wrong fittings?

Please contact and we will provide instructions to return the un-used fittings for an exchange or refund.

What if you don't carry the fitting I need?

We are constantly expanding our selection to meet the needs of the community. Please tweet us @CapTubes or email with your printer or hotend, and the specs of the fittings you need.

Frequently Asked Questions    How To Install    Choosing Your Tubing    Measuring Your Filament