Aijiren headspace screw vials are precision-threaded, making them an excellent choice for dependability and ease-of-use. They come in two sizes, 10 mL, or 20 mL in either clear or amber glass. Aijiren headspace screw caps are 18 mm and provide a tight seal and reproducible headspace results. Septa materials include PTFE/silicone and PTFE/butyl.