Autosampler Vials,Headspace Vials,Chromatography . Autosampler Vials,Headspace Vials,Chromatography Vials,Laboratory Vials-Aijiren Vials for HPLC/GC. The Screw Neck Cap produced by Aijiren is often used with 18mm Headspace Vial. The material usually used is Magnetic Metal with an 8mm center hole.