Tube: Color: Blue Length: 3m (1.5m/Pcs) Inside Diameter: 2mm Outside Diameter: 4mm Feature: Smooth surface, Non-stick & Corrosion resistance.Environmentally friendly and pollution-free & Durable.Self-lubricating: can convey materials smoothly with the smallest friction coefficient.High&low temperature resistance: usable temperature -190 C 260 C, almost unaffected by temperature.An extremely precise internal diameter can reduce the "wiggle room," or buckling, inside the tube, allowing you to print flexible filaments even for the longest Bowden systems.Fittings: 1.PC4-M6 fitting Inner diameter(blue end): 4mm Thread: 6 mm Material: copper and plastic 2.PC4-M10 fitting Inner diameter(black end): 4mm Thread: 10 mm Material: stainless steel and plastic Use: Install: connecting by the outer thread of the quick fitting.Remove: press and hold the blue or black end of the quick fitting and pull out the tube.Advantage: The upper part can be inserted outer diameter 4mm PTFE tube and self-locking.2 end connections of quick fittings are able to bear greater and stronger impulse but won't come off.