20mm Crimp seals with prefitted septa for headspace vials. Seals with pre-inserted septa are convenient and minimize contamination due to handling. Use magnetic seals with CTC/Leap™ Technologies, Gerstel™ and other magnetic transport autosamplers. PurePak™ PTFE/Silicone seals are packed in glass jars to maintain purity up to the point of use.