Tube: outer diameter: 4 mm; inner diameter: 2 mm; it is made of high-quality PTFE material, which is safe and non-toxic, odour-free, self-lubricating, heat-resistant up to 260 °C PC4-M6 fittings: copper and plastic material, durable and sturdy; thread: 6 mm; inner diameter (blue end): 4 mm, fit for the tube whose outer diameter is 4 mm PC4-M10 fittings: stainless steel and plastic material, anti-oxidation, anti-corrosion, and high hardness; thread: 10 mm, inner diameter (black end): 4 mm, fit for the tube whose outer diameter is 4 mm Easy to Install: the Extruder Fittings are PC4-M6 and the Hotend Fittings are PC4-M10, the Upper Part can be Inserted Outer Diameter 4 mm PTFE Tube and Self-Locking Compatibility: compatible with 3D printer 1.75 mm filament and other devices, Weight: 0.125 pounds, Manufacturer: AEDIKO