FILTERS Each filter has a magnetic ring tower in the center of the filter to remove metal particles under 10 microns which might have travelled through the filter wall. They also have built-in, correctly-calibrated pressure relief valves and one-piece cans with fully-rolled and safetycrimped edges to protect against leakage. These high-performance RevTech® oil filters have more paper folds than our Premium® spin-on oil filters resulting in 30% more filtering surface and the filter paper lasts 30% longer. Great for those high-performance and stock motors.