I always used to speak highly of the K&N filters due to the handy nut on the end, until i tried to undo one during a filter change and it rounded off like marzipan, and was also not any particular size, i couldn't get any socket to fit it properly so had to rely on the trustee chain wrench which never fails.
Apart from that minor gripe the filter did it's job okay.
Some people have been known to tape small magnets on oil filters to attract metal particles and stop them from circulating back into the engine.