Clear silanized vials with PP (polypropylene) lined, non-slit silicone septa screw caps. Recommended for PFAS analysis. LCMS testing showed no presence of PFAS in the septum; suitable for low-level PFAS analysis. Septum thickness 0.040", durometer 35-60 for easy piercing. Reseals for repeat injections, unlike a membrane-type PP cap. For vials only, use 220-97331-65; for caps only, use 220-97331-91 (100/pk), 220-97331-92 (500/pk), or 220-97331-93 (1000/pk.) NOTE: these show online as "Special Order" because they are packaged to order as a kit at SSI. If the component vials and caps are in stock (shown below as Related Products,) the kit will ship promptly.