Features Brass + PTFE: Made of high quality brass + PTFE material, which has good heat resistance, up to 260℃, safe and non toxic Long Life: This is PTFE tube + pneumatic fitting kit, easy to install, convenient, fast, sturdy and durable, and has long service life Application: This kit is small in size, simple and flexible in structure, used for 3D printer 1.75mm filament M6 feed connector PTFE Tube: This is PTFE tube, which has outer diameter of 4mm, inner diameter of 2mm, and a length of 1m, which is easy to use PC4-M6 Pneumatic Connector: This is pneumatic connector, the inner diameter (blue end) is 4mm, the thread is M6, 3mm Package List 2 x PTFE Tube 4 x Pneumatic Straight Connector