There are 6ml, 10ml, 20ml, round-bottomed, flat-bottomed with screw or crimp Headspace Vial. Aijiren 20ml Headspace Vial for Gas Chromatography. There are flat bottom and round bottom of 20ml headspace vial. Aijiren is 20ml headspace vial manufacturer, welcome to inquiry the supplier. 20mm Crimp Top GC Glass Vials for Lab Analysis.