18mm Screw Neck Headspace Vial for GC--Aijiren HPLC Cap Color Silver Septa details White, Red, Blue, 1.3-1.6mm thickness. Material Aluminum for Cap, PTFE/Silicone for Septa Package 100pcs/Pack Cap type Open top Septa type Non-slit Description Headspace vials from Aijiren Technology, Inc with high quality