We supply autosampler vials, septa and caps at factory price. 18mm Screw Thread Headspace Vials are often used in Shimadzu, Spectral Physics, Varian, and other autosamplers. 18mm Screw Thread top septa is used PTFE and high-quality silicone rubber or ultra-pure silica as raw materials, the gasket is guaranteed to be non-toxic. 1.