Beduan Pneumatic Plastic Bulkhead Union Fitting 12mm Tube OD x 12mm Tube OD Push to Connect Air Fitting (Pack of 2)

works great

I grabbed these for use with the 4mm OD PTFE tubing used on my Prusa printer so that I could make a custom rack for holding spools and feed it into my MMU3. These fit the stock tubing perfectly. As far as fit from end to end, thats going to be something each person has to do to taper the PTFE, but this will work and works for me.

Nice product

Got these to make a pass through of my drying chamber (3d printing) and they work as they should. I was hoping to pass the PTFE tube straight through but it seems like they have an internal stop to prevent that. Couldn’t tell you how well they work for pneumatics.

This product has saved me from so much headache of trying to design a proper, no friction fitting for my enclosure. I literally do not know how I have not found this product earlier or why nobody has suggested them - they are pivotal to designing a frictionless AMS system

Works as they should. Used to fit a cereal containers. With ptfe tube from the sealed box to the extruder drive

Nicely made unions make crossing an airline through a bulkhead quick and easy. I got these to punch through a plastic project box but there's enough thread on there to get through a quarter inch, easily. No leaks on 6mm OD line. They work well and were reasonable priced.

You can find gasketed tupperware containers and use these as bulkhead fittings for 3d printer tubes to keep the filament dry and clean. They screw in from both sides and work well for fitting on both sides of the container.