The vial has an 18mm outer diameter, which is a standard size for screw-cap headspace vials. It is designed to hold gas or liquid samples for analysis. The material of Headspace Vials is low extractable Borosilicate glass with a low expansion rate, high-temperature resistance, high strength, high hardness, high light transmittance, and high chemical stability. Headspace Vials are suitable for headspace analysis of volatile solids and gases. A headspace vial is used in the process of top–gas chromatography. When detecting volatile or semi-volatile mixtures with high boiling points, we need to heat them to vaporize them at the top. In this process, since the liquid samples are at the bottom, the material in the top gas can be measured without touching the liquid in the sample vial.