Chromatography Vials, Caps, Septa & Inserts, Tubes, Crimper, Syringe Filter-Zhejiang Aijiren Technology,Inc. - 10-20mL 18mm Screw Thread Headspace 10mL & 20mL screw neck ND18 rounded bottom headspace vials with matched 18mm magnetic precision screw metal caps, 17.5mm PTFE/silicone septa.