The associated 9 mm vial screw cap comes with your choice of septa constructed from either PTFE/silicone, PTFE/silicone/PTFE or PTFE/natural red rubber. Our screw vials and vial screw caps are designed for both HPLC and GC instrument platforms across a wide variety of applications, including pharmaceutical, environmental, energy and fuels, forensics, materials science, biopharmaceutical, proteomics, and metabolomics.