3 mm OD x 2 mm ID PTFE Teflon Tubing 6" Thermal Barrier Tube for 1.75 mm filament 3D Printer Hot End Bowden Extruder (3mm2mm MK8/MK9) Flashforge Creator X/CTC Bizer/Makerbot Replicator clones 6 inches of PTFE teflon thermal barrier tube for 3d Printers 3mm OD 2mm ID found in MK9 models like CTC printers and some other similar Replicator Clones Bowden teflon tubing is designed for 1.75mm filament