I used those kinds of filters right before my Vormax filter when I was trying to diagnose my fat-clogging problems(wasn't cold filtering). They always did a great job of catching a good deal of the fat, enough to save the big expensive filters. I'm not sure of their micron rating but they did pull the fat out of the oil. In my opinion they're cheap and seemed to work well.

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo