Oct 28, 2021 · Cap/Septum has a natural Pre-slit Blue polytetrafluoroethylene (PTFE) and white silicone septa are convenient and minimize contamination from handling.Cap/Septum tested by head space GC to ensure proper curing of silicone polymer.2ml HPLC Vials caps and septa with most close space tolerance and caps and septa meet standards set