Wide Openning Chromatography Vial Factory AMT™-Aijiren 2ml wide opening gas chromatography vials metal cap Perkin Elmer-Headspace Vials 2021 - 07 - 06. 18mm Screw Top Headspace Vial optional capacity is 10ml 20ml, the specifications are: 22.5*46mm, 22.5*75.5mm, providing headspace vials in both colorless and brown colors.