I emailed Pentius Filters & asked about their PCXL filter efficiencies. This is what they emailed back to me below. They confirmed this is not just for an individual filter but would not give me the tested filter they used or how many they used. They claim 99%@20 on their website but I've learned that advertising is not always what it seems. Still good efficiencies though & I would still run this filter if the construction was good. From what I've saw with 1 filter for my truck is that they are built in South Korea.
Pentius CustomerService email]>
Customer Service
Pentius Automotive Parts
(877)852-5000
Pentius CustomerService email]>
Customer Service
Pentius Automotive Parts
(877)852-5000