These high-quality pneumatic push-fit couplings have a 1/8" thread and screw directly to the bowden heat sink or any printed parts you may have that need to be converted to take PTFE tubing.
For 4mm OD Tubing:
Nominal Thread Size: 1/8" BSPT
Thread Length: 10mm
Overall Height: 25.5mm
Protrusion from Heatsink: 15.5mm