If I recall from what I saw about them in previous posts they are made in china and most people say they look like a Donaldson knockoff in the way they are constructed, but with plain paper filter media.
Honestly I would go for a Purolator classic for just a little more money.
They have metal ends, at least mine did when I cut it open. Everything I have read indicates Chinese made look a like of something else, not Purolator.
My big complaint was the ADBV, which seems to be the most common complaint when I see complaints. Other than that, I don't believe there are efficiency specs. Personally I'd go with a Purolator.