I just received these from Aliexpress: https://www.aliexpress.com/item/32856314896.html and they are perfect. Capricorn bowden fits all the way through, and they slide into my Bondtech extruder without any issues.

Be sure to choose the all-metal connectors with the white shim on the screw side, not the black plastic top ones.

Happy printing!

But, I have question. I instsall tjat pneumatic connectors and after that, I cant printing many times, because bowden tube is slightly pushed out of heatbreaker and fillament then fill that gap and stop moving to head. Have someone same problem?

Thanks.

https://www.amazon.de/-/en/gp/product/B0B6C6G2BN

So my brass olive broke free from the tube so I needed a replacement and I ordered this.

The thing just came today and I immediately put it to work. 

The nut goes in fine, I only need one as I have the revo micro on the other end. The tube isn't transparent but it's okay as my capricorn wasn't too.

The little pneumatic stopper is too big though, I can't fit it back in properly if the tube is in place.. Looks like I'll be printing a new one soon..

Overall, just happy I can print again and never have to worry about brass olives slipping out of the tube..

https://www.bondtech.se/product/pipe-fittings-set-for-prusa-mini/

looks like they finally came through this this connection...has anyone tried it?

After many searches I found a PC4 M8x1.25 which allows to pass the ptfe tube all inside.

Tested and working perfectly on my Bondtech extruder.

https://fr.aliexpress.com/item/4000907484781.html

This is the coupler for GTA2 extruder from Geeetech, for A10M etc.

Posted by: @micke-2

I contacted bondtech to get an update on the fittings that @JMN mentioned and got the following reply:

 

Our latest design is in the machine shop for prototype manufacturing.We still have some additional weeks before we have something well tested and good to launch.

So I did a hybrid approach with the PC4s.  I drilled the extruder side PC4 fitting for pass-through using a 4.1mm drill.  The hotend  PC4 fitting was stock, i.e., not pass though.   I shortened the hotend PTFE tube by 3mm to better accommodate the PC4 fitting as I measured. I also used a short piece of 4x5mm carbon fiber tubing on the upper end of the hotend PTFE tube to pilot into the 5.1mm ID of the PC4 fitting threaded end.  The upper end of the hotend PTFE tube gets a 45^ inside chamfer. (And the bottom end gets a 30^ outside chamfer to match the seat in the Mini heatbreak tube.)

I removed the filament sensor as I felt this was a  major friction component in the Bowden feeder system, and I really don't need that feature.

A 294mm Capricorn XS tube is used between the extruder and hotend, and am using Capricorn TL material for the input and hotend tubes.  I don't like the opaqueness of the XS tubing and if its 1.9mm ID causes problems I'll switch to the TL material for the long tube.

Pleased with the results using test pieces. (retraction at 1.7mm).

I left a bit of ptfe tube inside the extruder, like @fuchsr said.
I actually think that leaving a bit of tube inside the extruder or heatbreak is better. In that case you will have less play when the long tube is moving in the connector, as could happen as the carriage is moving all the time. I guess the heatbreak is more prone to clogging when the ptfe tube has been pushed all the way in. If there is a small piece of non-moving ptfe chances are lower, me thinks.