Graver's “absolute” rated PME cartridges are an economical choice for applications requiring “absolute” rated filter efficiency. We keep putting “absolute” in quotation marks. Why? Because Graver's PME filters are designed to be close enough to absolute efficiency for many applications, but they are not necessarily a replacement for a truly absolute-rated membrane filter.

PME is a depth filter—albeit a very efficient depth filter—so you can't bubble point or otherwise integrity test PME filters to ensure they are integral. Thus, they are “absolute” rated in quotation marks.

If you need to achieve true, verifiably sterile filtration—i.e. you need to be sure that you're filtering out nearly 100% of particles at a given size—you still need a truly absolute-rated PES membrane filter like Graver's ZTEC WB. PME filters are, however, rated at 99.98% efficiency, so they make a good filter for applications where close enough is good enough.

PME filters ship in packs of twelve directly from Graver's manufacturing plant in Delaware. The lead time is typically about 2–3 weeks to ship from Graver, plus time in transit to you. They're a great value, so plan ahead accordingly.