The associated crimp caps come with a choice of either PTFE/silicone, PTFE only, natural red rubber, butyl, or PTFE/butyl septum materials. Our 2 ml crimp top vials and 11 mm crimp caps are the perfect fit for HPLC and GC instrument platforms across a wide variety of applications, including pharmaceutical, environmental, energy and fuels, forensics, materials science, biopharmaceutical