Bowden line teflon tubing is for 1.75mm filament. 4mm OD 2mm ID, length is 2 Meters.Two PC4-M6 push-in tube fittings are also included in this kit. Package contents: 1 x 2 Meter PTFE/teflon tube.2 x PC4-M6 Brass Fittings for 4mm OD Tube with M6x1 Threads.